DEVELOPI\-iENTS IN SEl)IMENTOLOGY
9B
DEVELOPMENTS IN SEDIMENTOLOGY 9B
CARBONATE ROCKS Physical and Chemical Aspects ...
121 downloads
1342 Views
20MB Size
Report
This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below!
Report copyright / DMCA form
DEVELOPI\-iENTS IN SEl)IMENTOLOGY
9B
DEVELOPMENTS IN SEDIMENTOLOGY 9B
CARBONATE ROCKS Physical and Chemical Aspects
EDITED BY
GEORGE V. CHILINGAR Professor of Petroleum Engineering University of Southern California, Los Angeles, Calif. (U.S.A.)
HAROLD J. BISSELL Professor of Geology Brigham Young University, Provo, Utah (U.S.A.) AND
RHODES W. FAIRBRIDGE Professor of Geology Columbia University, New York, N.Y. (U.S.A.)
ELSEVIER PUBLISHING COMPANY Amsterdam London New York 1967
ELSEVIER PUBLISHING COMPANY
335 JAN VAN
GALENSTRAAT, P.O. BOX
21 1, AMSTERDAM
AMERICAN ELSEVIER PUBLISHING COMPANY, INC.
52 VANDERBILT AVENUE, NEW YORK, N.Y. 10017
ELSEVIER PUBLISHING COMPANY LIMITED RIPPLESIDE COMMERCIAL ESTATE, BARKING, ESSEX
LIBRARY OF CONGRESS CARD NUMBER
WITH
65-20140
80 ILLUSTRATIONS AND 70 TABLES
ALL RIGHTS RESERVED THIS BOOK OR ANY PART THEREOF MAY NOT BE REPRODUCED IN ANY FORM; INCLUDING PHOTOSTATIC OR MICROFILM FORM, WITHOUT THE WRITTEN PERMISSION FROM THE PUBLISHERS PRINTED IN THE NETHERLANDS
CONTENTS
CHAPTER 1. INTRODUCTION R. W. FAIRBRIDGE (New York, N.Y., U.S.A.), G. V. CHtLINGAR (Los Angeles, Calif., U.S.A.) and H. J. BISSELL (Provo, Utah, U.S.A.) . . . . . . . . . . . . . . . . . . CHAPTER 2. ELEMENTAL COMPOSITION OF CARBONATE SKELETONS, MINERALS, AND SEDIMENTS K. H. WoLF (Canberra, A.C.T., Australia), G. V. CmuNGAR (Los Angeles, Calif., U.S.A.) and F. W. BEALES (Toronto, Ont., Canada) . . . . . . . . . . . . . . . . . . CHAPTER 3. PHYSICAL CHEMISTRY OF FORMATION OF CARBONATES W. H. TAFT {Tampa, Fla., U.S.A.) . . . . . . . . . . . . . CHAPTER 4. CHEMISTRY OF DOLOMITE FORMATION K. J. Hsu (Riverside, Calif., U.S.A.) . . . . . . . . . . . .
23
. .
151
. . . . . .
169
CHAPTER 5. STABLE ISOTOPE DISTRIBUTION IN CARBONATES E. T. DEGENS (Woods Hole, Mass., U.S.A.) . .
193
CHAPTER 6. INFLUENCE OF PRESSURE AND TEMPERATURE ON LIMESTONES 209 B. L. MAMET (Bruxelles, Belgium) and M. o'ALBISSIN (Paris, France) . . . CHAPTER 7. THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
J. M. HUNT (Woods Hole, Mass., U.S.A.) . . . . . . . . . . . . . . . .
225
CHAPTER 8. TECHNIQUES OF EXAMINING AND ANALYZING CARBONATE SKELETONS, MINERALS, AND ROCKS . K. H. WOLF (Canberra, A.C.T., Australia), A. J. EASTON (London, Great Britain) and S. WARNE (Newcastle, N.S.W., Australia) . . . . . . . . . . . . . . . . . . • • . 253 CHAPTER 9. PROPERTIES AND USES OF THE CARBONATES F. R. SIEGEL (Washington, D.C., U.S.A.)
343
REFERENCES INDEX
395
SUBJECT INDEX . . .
404
Chapter 1
INTRODUCTION RHODES W. FAIRBRIDGE, GEORGE V. CHlLlNGAR AND HAROLD J. BISSELL
Columbia University, New York, N. Y. (U.S.A.) University of Southern California, Los Angeles, Calif. (U.S.A.) Brigham Young University, Provo, Utah (U.S.A.)
Carbonates constitute some 10-15 % of the sedimentary rocks of the earth’s crustl, as well as contributing to some important igneous and metamorphic rock types. Thus high- and low-temperature carbonate types are recognized, but in this book the authors are considering almost exclusively the latter. Field and laboratory investigations of ancient sedimentary carbonate rocks must of necessity be extended beyond the realm of origin and classification only, and should take into consideration the physical and chemical properties of these sediments. In order for these studies to be scientific and meaningful, careful research of such properties of modern carbonate sediments must be undertaken on a scale ranging from world-wide field investigations to all those detailed laboratory techniques now known to sedimentary petrologists and petrographers. Realizing that the bulk of ancient sedimentary carbonate rocks accumulated in various depocenters of the marine realm, researchers have directed most of their attention to this environment in an effort to learn more of the physical processes of desiccation, compaction, expulsion of interstitial water, congelation, pressure-cohesion, grain orientation, and others. Furthermore, serious study is also being made of sedimentary structures which heretofore were thought to be present only in sandstones; included among these sedimentary structures are various types of crossbedding, ripple-marks, mud-cracks, bottom markings, slump structures, rippledrift lamination, and many more. Certain coarse carbonate deposits have been identified as turbidites, and theories have been advanced to account for their mode(s) of origin. All in all, geologists desire to know the entire spectrum of processes, physical, chemical, biologic, and their combinations, which lead to ultimate lithification of carbonate sediments. Factors involved include compaction, pore reduction, expulsion of interstitial fluids and gases, pressure-cohesion, cementation, crystallization and recrystallization, dolomitization, silicification, bacterial effects, and introduction of authigenic or metasomatic substances such as iron, sulfates, and Some estimates run as high as 25% by volume (CHILINGAR, 1956d). All calculations must be revised, however, in the light of drilling beneath the oceans. At the present time none of the 10%. estimates is likely to be correct by
+
2
R. W. FAIRBRIDGE, G. V. CHILINGAR A N D H. J. BISSELL
phosphates. Lime-muds of modern repositories contain as much as 80% water, suggesting that ancient lime-muds had comparable water contents; when these sediments dehydrate they become denser and resultant shrinkage is taken up by physical compaction of the sediments. (1959, p.298), several firmly settled, modern calcareous According to WELLER sands have been observed to have porosity between 50 and 60% (or more), which is higher than that of quartz sand (37%). Not many limestones, however, retain more than 10% porosity; numerous limestones practically are non-porous. According to recent research by ATWATER (1965) on sandstones, burial to 30,000 ft. results in a reduction of porosity to 2.5% (largely through intergranular pressure solution); the almost total loss of porosity in medium- to fine-grained limestones under similar burial may well be predicted. Inasmuch as empty shells and porous structures are not crushed in many coarse-grained carbonate rocks, consolidation was probably accomplished at an early stage before being subjected to much overburden pressure (WELLER,1959, p.298). The time and conditions of consolidation of many limestones by cementation are uncertain. The question of whether the calcareous muds compact less readily than clay or not still remains to be answered. The weight of overlying sediments, however, is obviously an important factor in compaction. High-pressure (up to 200,000 p.s.i.) compaction studies were conducted by RIEKEet al. (1964) on the hectorite clay from Hector, California, containing 50-58% by weight of CaC03. The remaining moisture content versus the logarithm of pressure curve was similar to those of pure clays. No significant changes in the X-ray pattern have been noticed by these writers. The chemical composition of modern sea water is approximately the same over the very large expanse of the oceans; in the littoral zone, however, and particularly near the mouths of rivers, there is dilution of the ocean water by fresh water. The dissolved solids in ocean waters (volume = 1.37 * lo9 km3; specific gravity = 1.05) amount to 5 1016 metric tons, assuming an average salinity of 35%,, (SVERDRUP et al., 1952, p.219). The composition of sea water is presented in Table I. In addition to the ions listed, there are over 36 others elements present. Material contained in sea water is chiefly in ionic form. Only a small part of total solids occurs as colloids in different degrees of dispersion, these being chiefly clay particles and some organic matter. Various organisms are present, and ocean water contains atmospheric gases in varying amounts depending on depth and the history of the water mass. It must also be realized that the form of some of the elements in sea water is far from being known, and various changes of local or regional significance, such as the COz content, influence ionic equilibrium. As shown in Fig.1, the order of increasing solubility of various chemical compounds of sedimentary deposits is as follows: Al, Fe, Mn, SiOz, Pz05, CaC03, CaS04, NaCl, MgC12. The solubility depends on the following physicochemical factors: (I) pH; (2) Eh; (3) COz content; ( 4 ) chemical composition of solution; (5) size of dissolved particles; (6) temperature; and (7) pressure. It is obvious, therefore, that any at-
3
INTRODUCTION
TABLE I (CHIEFCOMPONENTS)~
CHEMICAL COMPOSITION OF SEA WATER
Ion
Percentage of dissolved solids
mg/kg*
Percentage equiv.
Na+
30.62 (S)
10,707 (A) 387 (A) 1,317 (A) 449 (A) 19,343 (A)
38.50 (A) 0.82 (A) 8.95 (A) 1.73 (A) 45.10 (A)
2,688 (A) 13 (s) 4.7 (S)
4.63 (A)
K+
1.10 (S)
3.69 (S)
Mg2+ Caa+ CIBrHCO3Co&
1.15 (S) 55.04 (S)
0.41 (S)
sod2-
7.68 (S)
Sr2+ B3+ Sr2+, H3B03, Br'A
=
0.31 (S)
After ALEKIN(1953, p.269); S
*See also Appendix A.
=
After SVERDRUP et al. (1952, pp.214, 220).
tempt at understanding physical and chemical aspects of present-day marine sediments must take into account these variables; however, the extrapolation of the data so gained to interpret the origin of ancient sediments has inherent hazards. Still, with the full realization of all these uncertainties, tremendous and significant advances are being made. For example, a research program into some / A
J
ii
/
1.000
/
A
/
/ "/ / /
- 0
/b
O
.o 0' d
Fig.1. Solubility(mg/l) ofvariouschemicalcomponents of sedimentary rocks in water at atmospheric pressure. (After RUKHIN,1961, p.275, fig.10-IX.)
4
R. W.
FAIRBRIDGE, G.
V. CHILINGAR AND H. J. BISSELL
of the aspects of mineralogy and chemistry of modern, unconsolidated carbonate sediments of southern Florida, the Bahama Islands region, and Espiritu Santo Island (by TAFTand HARBAUGH, 1964) was undertaken to understand better the relationships of different carbonate minerals in different sedimentary environments. One significant result of the study was the lack of evidence to suggest that either aragonite or high-magnesium calcite is being transformed to low-magnesium calcite within the unconsolidated sediments which were investigated. It was suggested by these workers that inversion or transformation are not taking place because the concentration of magnesium ions in the water surrounding the mineral grains in the sediment is high. The high concentration of magnesium ions in interstitial water apparently prevents transformation of aragonite and high-magnesium calciie. The role of the various trace elements, notably Mg, Sr, Mn, Pb, etc., in controlling the precipitation and stability of the metastable carbonates, especially aragonite and high-magnesium calcite, has received considerable attention in recent years. GOTO(1961) has shown that the solvation effect of the water molecules is critical in loosening the atomic bonds of carbonate minerals of distinct structural densities, and is hindered at elevated temperatures. Experimental work has shown that the crystal form is closely controlled by the ionic concentrations. SANDERS and CRICKMAY (1945, pp.25 1-253) discussed the chemical character of Quaternary and Tertiary limestones of Lau, Fiji, in &e Southwest Pacific. Particular emphasis was placed on investigating dolomite content. They observed that dolomitization seems to be unrelated to the fossils present. Coral rocks are generally no more dolomitized than algal rocks; but, in any particular dolomitic rock, dolomite is most abundant in corals and least abundant in Algae and echinoids. Furthermore, replacement by dolomite appears to be roughly dependent on solubility of skeletal remains, being most common in the easily soluble aragonite shells. It was also noted that dolomitization is related to original texture: permeable reef rock and calcarenites are usually the most strongly dolomitized. These two examples are mentioned for the single purpose of calling attention to the benefits of field-oriented research into physical and chemical aspects of modern sedimentary carbonate materials, but can equally well apply to all carbonates ranging from those forming today to those as old as Precambrian. Such work must involve careful studies of elemental composition of marine organisms as well as those of the sediments themselves. As pointed out by VINOGRADOV (1953, p.16), . the fate of some chemical elements . . . is connected with their accumulation in the sediments so that much clarification is still needed in regard to the study of the elemental composition of marine organisms which extract a large number of elements from the sea and concentrate them a hundredfold or a thousandfold in the sediments, silts, and so forth." The monumental study by VINOGRADOV (1953) has contributed substantially to our knowledge of the geochemistry of the sea. For the better understanding of physical chemistry of dolomite formation, two figures may be consulted. Fig.2 shows the region of dolomite formation in
". .
5
INTRODUCTION
Fig.2. Region of dolomite formation in saturated chloride and sulfate solutions. (After VALYASHKO, 1962, p.57, fig.14.)
Fig.3. Solubility of CaC03-MgC03-HzO system at Pco,=l atm. and Pc0~-0.0012 atm. and temperatures ranging from 0" to 70°C. Points between ordinate and 45 "-line represent solubility of calcite-dolomite mixtures, whereas those between 45"-line and the abscissa represent dolomitemagnesite mixtures. The amounts of Mg(HC03)z and Ca(HC03)z are expressed in mmole/l ,OOOg solution. (After YANAT'EVA, 1950, 1954; also see CHILINGAR, 1956a; BARONand FAVRE, 1958.)
-
saturated chloride and sulfate solutions, and Fig.3 indicates the solubility of the CaC03-MgC03-HzO system atpcoz 1 atm. and temperatures ranging from 0 to 70°C. In Fig.3, the points of intersection between the bisectrix and dolomite saturation curves show the composition of solutions saturated with respect to pure dolomite, whereas the solubilities of pure CaC03 and MgC03 are shown on the ordinate and abscissa, respectively. On the other hand, the solubilities of mixtures of dolomite calcite and dolomite magnesite (two-phase) are shown by the junction (nodal) points. The curve connecting these junction points to the left of bisectrix represents solubility of mixtures of dolomite and calcite, whereas the one
+
+
6
R. W.
FAIRBRIDGE, G.
V. CHILINGAR AND H. J. BISSELL
at the right of bisectrix represents mixtures of dolomite and magnesite. In all cases, the magnesite had the highest solubility; dolomite was least soluble. If the solubility of carbonate rock is determined and plotted on Fig.3, the position of the point on the diagram could indicate the presence of: ( I ) CaCOs alone; (2) CaMg(CO3)z alone; (3) MgC03 alone; (4) mixture of CaC03 and CaMg(C03)~;and (5) mixture of CaMg(CO3)z and MgC03. On the other hand, the solubility of carbonate rock may be estimated if the mineralogical composition of carbonate rock is determined. More research, however, still remains to be done in this field. YANAT’EVA (1957) showed that the region of crystallization of dolomite at a given pcoZ reaches maximum proportions at temperatures between 30” and 45 “C. Inasmuch as pH in sea water tends to respond to and reflect (inversely) pcoZ in the atmosphere, one may conclude that dolomite is stable at a lower pH than calcite; thus, some of’the widespread dolomites of the Precambrian and early Paleozoic times may be primary precipitates out of ancient sea water of lower pH than that of today. Diagenesis of carbonate rocks and mechanism of dolomitization have been discussed recently in detail by CHILINCAR et al. (1967), and by various authors in a symposium edited by PRAYand MURRAY (1965). It is important to mention here that there are ever-increasing investigations of the role of microorganisms in primary precipitation of certain materials in oceans and lakes, as well as studies of diagenetic effects of these organisms. As pointed out by Oppenheimer in the introduction to the excellent work of KUZNETsov et al. (1963): “It can be presumed that much of the transition or diagenesis of inorganic elements and organic compounds in water and sedimentary environments takes place directly or indirectly through the activities of living microorganisms. These microorganisms are indigenous to all environments except volcanic high-temperature sites, and their abundance throughout the hydrosphere and surface of the lithosphere is evidence of their acitvity. They can withstand and be active at pressure up to 25,000 p.s.i., pH from 1 to 10, temperatures from 0 to 75 “C, and salinities up to saturation.” Evidence has been obtained which indicates probable existence of bacteria in sedimentary rocks in excess of 3 billion years. Microorganisms probably have been present in all sedimentary realms throughout all geologic eras and accordingly have affected sedimentary processes. Data on simultaneous deposition of calcite, dolomite (or magnesium calcite) and sulfur, and the role played by bacteria, are not abundant. It would appear that at least two principal mechanisms by which microbiological processes can lead to formation of sulfur in syngenetic deposits have been noted. One is the formation of molecular sulfur by bacteria in a bioanisotropic body of water rich in hydrogen sulfide; the sulfur sinks and is buried in bottom lime-mud. The second is that sulfides can form by reduction of sulfates in water-rich oozes, and after diffusion to the surface layer will be oxidized to molecular sulfur by the bacteria. Such an example seemingly is the bioanisotropic Lake Belovod (U.S.S.R.), which has been described by DOLGOV (1955). Microscopic studies of the surface layer of ooze proved the presence of
INTRODUCTION
7
new crystals of calcite, having been formed by oxidation of calcium sulfide and by the photosynthetic activity of the phytobenthos. One would suppose that molecular sulfur can be deposited in bodies of water only when hydrogen sulfide is formed at a very high rate in the lime oozes. Here, again, is a problem requiring further study. The present book, Carbonate Rocks, Volume B, is an integrated effort of many scientists to bring into sharp focus the tremendous amount of data, ideas, and concepts of physical and chemical aspects of carbonate sediments. The chapters by different authors are reviewed in the order of their appearance in this book. In the opinion of the editors, the volumes (Carbonate Rocks, A and B) represent some of the best thinking of researchers and teachers in this field today. These are people whose lives are dedicated to the development of new ideas and concepts, and to a rigid application of the scientific method. The latter calls for imagination, indeed intuition, but patient testing and practical demonstration are inherent requirements. Although it is now more than 100 years since Henry Sorby first cut a thin-section of limestone, and even longer since Charles Darwin described the modern carbonate environments of the tropic seas, the “loose ends” are numerous and fundamental mysteries still persist as a constant and exciting challenge to successive generations.
ELEMENTAL COMPOSITION OF CARBONATE SKELETONS, MINERALS, A N D SEDIMENTS
Factors determining elemental composition of sedimentary carbonate rocks fall into three groups: (a) initial physicochemicalfacfors (nature of solutions and ions, pH, Eh, temperature and pressure, rates of reactions, etc.); (6) organic factors (direct and indirect metabolic effects, reworking, bacterial processes-even long after burial); and (c) inorganic (diagenetic) factors (modifications to the sediment during and after burial). Numerous components occur in carbonate rocks in only trace amounts; yet in certain cases they appear to play decisive roles. Solid solution (isomorphous) series are particularly important. Of possible importance are the following elements: Mg, Mn, Ni, Fez+, Sr, Ba, Pb, Co, Zn, Ca, Cd. Binary series are better known than polycomponent systems. Some research is being conducted on the possible use of fluid inclusions as indicators of paleoenvironments (either synsedimentary or diagenetic). In Chapter 2, K. H. Wolf, G. V. Chilingar and F. W. Beales discuss the elemental composition of carbonate skeletons, minerals and rocks. They also describe the factors and processes determining the elemental composition; both inorganic and organic processes were covered in considerable detail. The numerous chemical components of carbonates occur in what has been usually termed major, minor and trace quantities. Some elements occurring as traces under certain conditions, are present as minor or even major components
8
R. W. FAIRBRIDGE, G. V. CHILINGAR AND H. J. BISSELL
under other physicochemical or biochemical influences. On the other hand, certain elements never occur in concentrations beyond that of minute traces in carbonate skeletons, minerals and rocks due to numerous reasons. According to DEERet al. (1962), the following elements have been recorded: (1) calcite-Mg, Mn, Fez+, Sr, Ba, Co, Zn; (2) aragonite-Sr, Pb, Ba, Mg(?), Mn(?); (3) dolomite-Fe2+, Mn, Pb, Co, Ba, Zn, Ca, replacing Mg; less commonly Mn, Fe, Pb, and Mg substituting for Ca; ( 4 ) ankerite-Fe2+, Mn; (5) siderite-Mn, Mg, Ca, Zn, Co; (6) magnesiteFe2+, Ca, Mn, Ni, Co, Zn; (7) rhodochrosite-Ca, Fez+, Mg, Zn, Co, Cd; (8) strontianite-Ca; and (9) witherite-Ca, Mg. It should be noted, however, that many of the above minor and/or trace elements are from high-temperature carbonate minerals. Probably, future research will result in the finding of other elements in these minerals. Elements that occur in sea water in amounts higher than (p.p.m.) are concentrated by organisms 10-100 times that amount. Some of the elements present in the ocean water in quantities less than lO-5% (1 part per 10 million) are also organically utilized. Elements found in biological material and which can be classified as structural elements include C, H, N, 0, P, S, C1, Na, K, F, Mg, Si, and Ca; whereas Fe, Cu, B, Mn, and I are the biocatalysts. Due attention has been given by Wolf et al. to Ca/Mg and Sr/Ca ratios in both organic and inorganic carbonates; and their dependence on temperature, salinity, etc., of the depositional environment was discussed. It is interesting to note here that the maximum MgC03 content of inorganically precipitated calcium carbonate is approximately 4% in contrast to the maximum value of about 30% in organically formed carbonates. CHAVE(1954) demonstrated that aragonitic organisms seldom contain over 1% magnesium carbonate. The Ca/Mg ratio, therefore, also largely depends on the mineralogic form of the carbonate. Non-carbonate material is often present in carbonate sediments. A distinction between primary detrital components and authigenic (diagenetic) minerals is made. The presence of so-called “high-temperature” forms among the latter (e.g., quartz, feldspars, sphene, rutile, tourmaline, etc.) should no longer be a source of astonishment but rather should be used as indicator for reconstructing diagenetic environmental chemistry. The presence of considerable primary organic matter in a carbonate sediment is often the signal for the enrichment of the rock in a wide range of trace elements such as Mo, V, Ni, Pb, Cu, Ag, As, Ge, I and Br. The bacterial liberation of H2S in the syndiagenetic stage is a significant “fixing” process. Inasmuch as some elements present in sea water in the merest traces are selectively concentrated by certain organisms by several orders of magnitude, the nature of the initial biota is of special significance. Among the organisms that are involved in the precipitation of carbonates, it is important to distinguish between (1) the higher phylogenetic groups that secrete carbonates into skeletal material; and (2) those-notably certain primitive Algaethat merely create a favorable microenvironment for precipitation by removal of
INTRODUCTION
9
COz and elevation of pH, and hold the fresh precipitate from dispersal by currents by mats of fine hairs or filaments. The latter are particularly significant in the Precambrian deposits; however, they are still observed in the living state today, particularly in lagoons and tidal flats, i.e., partially isolated but well-illuminated and oxygenated habitats (favoring vigorous photosynthesis). Much attention has been given to the ratios of the various carbonate minerals within sediments and their diagenetic roles. Aragonite/calcite, Ca/Mg, and Ca/Sr ratios, organic components, etc., are of significant importance in skeletal composition and reflect both environments and phylogeny. Of considerable interest is the discovery pioneered by ABELSON (1957), that proteins and amino acids in minute amounts may be analyzed from shells of great antiquity. Some, but up till now very little, attention has been given to the nature of invertebrate shell growth. Because of its biomedical significance,somewhat more is known of mammalian calcification. Isotopic analysis of skeletal material has proved to be illuminating; not only for paleotemperature work (1*0/l60 ratios), but also for salinity determination and for recognizing organic from inorganic microcomponents, notably carbon isotopes. The “law of minimum in ecology and geochemistry” can be’utilized successfully in environmental reconstruction. For developing exploration philosophies (notably in petroleum search) the geochemical techniques involved can be very helpful. As a result of diagenesis-epigenesis, which encompasses a large number of factors and mechanisms, there is an alteration in the content of major, minor and trace elements, and texture and structure of individual carbonate particles and whole rock units. Trace elements are mobilized by diagenesis-epigenesis and metamorphism. In relation to a chemical alteration of carbonates, the numerous diagenetic processes include: (I) inversion: aragonite-calcite; (2) conversion: high-Mg calcite-low-Mg calcite; (3) pseudomorphic replacement: carbonate by carbonate; (4) grain growth; (5) grain diminution; (processes 2-5 are commonly grouped and referred to collectively as “recrystallization”); (6) genesis of non-carbonate components; (7) solution, leaching and bleaching; (8) adsorption-diffusion-absorption; and (9) precipitation of carbonate: cement and nodules. Attention is given to ionic exchange and replacement during advanced diagenesis; compaction of sediments within any sedimentary basin forces migration of fluids, as stressed by NAGY(1960) in his “natural chromatography” concept. Low-grade metamorphism is sometimes induced. Special consideration has been given to an examination of the inorganic physicochemical conditions of precipitation. These conditions today appear to be of very little importance, but may have been predominant in many ancient deposits. Of interest for the idea of a “cold Precambrian” (FAIRBRIDGE, 1964) is ANGINOet al. (1964) recent observation of gypsum, aragonite and mirabilite precipitation in ice-covered Lake Bonney in Antarctica. The presence of dominant Mg in contem-
10
R. W.
FAIRBRIDGE, G.
V. CHILINGAR AND H. J. BISSELL
porary sediments has now been traced to a large range of environments, but always distinct from modern sea water; the implications for interpreting the nature of Precambrian-Paleozoic sea water are forceful but incomplete. A number of examples illustrating changes in the elemental composition with time through the geologic column are presented by Wolf et al. Some of the changes in contents of elements occurring from the Precambrian to the Recent are world-wide (Fig.4). The interpretations of the causes, however, are quite hypothetical and consequently are of a controversial nature. For example, the analyses of numerous limestone samples showed that there is a general increase in the average Ca/Mg ratio in going up the geologic column, with superimposed periodic fluctuations (see CHILINGAR, 1956~).One possible explanation for the evolution of dolomites is the selective return of calcium to the lands. There appears to be a selective weathering of calcium over magnesium in the sediments, and a gradual increase with time of Ca/Mg ratio in solutions contributing to the sea. Permanent loss of muds, which have very low Ca/Mg ratios,. from lands is another reason for the selective and permanent loss of magnesium from the continents. A possible reason for the decrease in Ca/Mg ratio since the Cretaceous time is the fact that pelagic Foraminifera started to extract great quantities of calcium out of the sea water and deposit it in the oceans during and after the Cretaceous time. This calcium is thus withdrawn from the cycle and never returned to the
50-
5 -
v)
n
z
a v)
4-
40I4
O
*
m
3u z
o 2
r
-
3 -
-
.
0
s
2-
'
0
a 4
I-
0,
Z
n
z
30-
0
t P 0
20
-
- .s r" 0
I -
10
CARBONATES OF 4''NORTH AUERICA
I
Pr 23 950
1 600
ABSOLUTE
TIM^
I
Pz
I
I
Mr
1
1Kr
225-m-0IN MILLIONS OF YEARS
Fig.4. Variation of CaO/MgO ratio in clays, sands and carbonate rocks with time. (After RONOV, 1964, p.723, fig.2.)
INTRODUCTION
11
Regional factors are of great interest in considering ancient environments. Arid shores will set up quite distinctive circulation patterns within a basin from temperate well-watered coastlines. Depth distribution can also play a critical role. In Paleozoic rocks dolomite was formerly often considered to be a deeper environmental indicator than limestones, but the evidence from cyclic sequences showed that in many cases the dolomite facies was near-shore (FAIRBRIDGE, 1957). On the Russian Platform through much of the Paleozoic a distinctive nature of circulation reversed this pattern, and phosphorites commonly mark the near-shore facies. Wolf et al. review in some detail the works of Soviet scientists Vinogradov, Ronov, Khain, Teodorovich and others on the changes in Ca/Mg and Ca/Sr ratios through time based on vast numbers of analyses made on the carbonate rocks of the Russian Platform. These results were also compared with the data from North America and the rather sparse information from elsewhere in the world. The modern Mg content drops to 1/25 of its Proterozoic value, whereas the Ca content rises 40% in the same period. Thus there is a marked decrease in the Ca/Mg ratio going back through time. TEODOROVICH (1960) suggested that there has been a progressive change in mode of carbonate genesis through time: (a) Precambrian-Early Paleozoic: direct chemical dolomites; (b) Late Paleozoic: both diagenetic and chemical dolomites; and (c) Mesozoic-Cenozoic: predominantly diagenetic dolomites. VINOGRADOV and RONOV(1956) have shown that these systematic changes affect cements as well as granular components, so that they must be a function of a secular change in environmental fluids, which in turn reflects the progressive evolution of the earth‘s crust. The dynamic nature of the latter, indeed, precludes any possibility that its composition should remain static, although one may visualize perhaps rapid, non-secular steps from one near-equilibrium condition to the next, as successive threshold levels are surpassed (FAIRBRIDGE, 1964). In this way, the total pco2, at or near the earth’s surface, derived basically from “juvenile” volcanic emanations, has been progressively rising through time, but has been controlled and in fact probably decreased sharply at certain stages by solid carbonate removal into buried sediments. Very large deviations of the pco2 through geologic time are ruled out by some scientists on two counts: (a) the buffering effects related to CaC03 solubility in sea water, and (b) the principle of biologic continuity through time, which will not allow gross changes in the atmospheric environment without destroying the planetary biota. Minor phylogenetic catastrophes are allowable and are believed to have occurred. It is believed from the geochemistry of the lithologic record that the pcoZdecreased slowly through the Paleozoic and Mesozoic times, culminating with the vast removal of c0a2-by pelagic plankton in the Cretaceous time. It would be interesting. for imaginative biologists to experimentally control the metabolism of selected primitive marine organisms under conditions of higher pco2, higher Mg2+ and lower Ca2+ concentrations.
12
R. W. FAIRBRIDGE, G. V. CHILINGAR AND H. J. BISSELL
PHYSICAL CHEMISTRY OF CARBONATES
Modern carbonates laid down in warm, shallow waters consist, for the most part, of metastable minerals (aragonite and high-magnesium calcite) that did not as a rule persist for long periods in the past. Ancient carbonates consist of dolomite and low-magnesium calcite. During lithification (diagenesis) alteration occurs either by solid-state recrystallization (thus preserving original structures as well as Sr/Ca, W / W , and 1 6 0 / 1 8 0 ratios) or by solution and reprecipitation (destroying original features and isotopic ratios). Experiments described by W. H. Taft in his Chapter 3 on the “Physical Chemistry of Carbonates”, show that the metastable aragonite recrystallizes to calcite within 100 days, if submersed in distilled water at room temperature. In nature, however, Holocene shallow marine aragonites maintained constantly in sea water for several thousand years are found to be perfectly preserved. It was found experimentally that the presence of large amounts of magnesium ions ,inhibited inversions; this is true also of strontium, but only in very high concentrations. Recrystallization is accelerated by the rise in temperature, by the presence of certain trace elements, or by the introduction of any ion that tends to lower the pH. Generally, when the natural aragonite or metastable calcite are exposed to rainwater, they rapidly invert to the stable forms. Aragonite forms the cement in beachrock; however, all beachrocks dating from a few thousand years have calcite cements, because during this time they have been subjected to leaching by rain and ground water. Occasionally, dolomite replaces the aragonite or high-magnesium calcite in quite modern deposits. The role of time in some carbonate reactions is just beginning to become recognized. Some dolomite does not form immediately, but instead the disordered form “protodolomite” forms, which only slowly becomes ordered. The protodolomite may be synthetically prepared if Ca2+ and Mg2+ ions are slowly introduced to the solutions containing CO&. For a detailed review on a synthetic formation of dolomite, one may consult CHILINGAR (1956b) and SIEGEL (1961). In sea water, S O P may form a complex with Ca2+ and thus raise the Mg/Ca ratio which is favorable for the dolomite formation. In nature, if a bed of shallow-water metastable carbonates becomes emergent (due, for example, to brief eustatic oscillation), it is likely to be quickly inverted to stable calcite. If, however, the platform is subsiding and the formation becomes covered by other sediments and is subjected to rising connate waters (“anadiagenesis”) rich in Mg2+ and S042- ions, a favorable situation may exist for dolomitization. An alternating (cyclic) sequence of calcitic limestone and dolomite could thus develop. On the other hand, the common association of Paleozoic dolomite layers with higher amounts of insoluble residues suggests rather that they belonged to shallower water environments (FAIRBRIDGE, 1957). Inasmuch as the latter are normally richer in the high-magnesium calcites and aragonites than deeper sedi-
13
INTRODUCTION
ments, the alternation may be controlled by primary differences in carbonate sediment type, which in turn may be in a cyclic sequence of eustatic origin.
CHEMISTRY OF DOLOMITE FORMATION
In Chapter 4,Dr. K. Jinghwa Hsu sums up the present state of knowledge on the long-puzzling problem of dolomite formation. He pointed out that not only must one consider the geochemical conditions appropriate for the formation of the mineral dolomite as a stable phase, i.e., simple discrete crystals, as in abyssal depths of g e northern ocean, but also for the large masses of dolomitic rocks in the geological record which indicate that such conditions must have persisted for considerable periods of time. Experimental data on dolomite formation under surface environments still contain much that is contradictory. For example, the solubility product of dolomite at 25 "C and a pressure of 1 atm., as determined by various investigators, ranges from 10-17 to 10-20. Unquestionably dolomite is present in very recent sediments within a few cm of the surface in some South Australian lagoons, in beachrocks of the Persian Gulf, in the West Indies, and elsewhere under about 1 atm. pressure. Equally well established is the presence of fresh dolomite rhombs in modern deepsea sediments under a pressure approaching 500 atm. and temperature of about 2°C. Under such contrasting conditions wide ranges of pH and Eh are observed; and there is little agreement among the geochemists concerning their respective roles. An increase of temperature, however, evidently increases the rate of dolomite formation. In synthetic dolomites, an elevated pressure has always favored the reaction. At relatively low pressure, GRAFand GOLDSMITH (1956) only obtained what they termed a protodolomite (calcic and with a disordered lattice). Dr. Hsu considers the free energy relations in three hypothetical reactions: CaC03
+ MgC03 + CaMg(CO3)z
(A)
In this case, confusion occurs because MgC03 is found to be not stable in water (marine or fresh) at room temperature and normal pressure, although the free-energy calculation suggests that it is. CaC03
+ MgC03.3Hzo + CaMg(C03)~+ 3Hz0
(B)
Experiments suggest that MgC03. 3Hz0, nesquehonite, is the stable magnesium carbonate in water below 80°C. 4CaCO3
+ Mg4(CO&(OH)z. 3Hz0 + COz + 4CaMg(C03)~+ 4Hz0
(C)
Hydromagnesite is the stable form where the pcoZ is very low. An aragonitehydromagnesite mixture was found as a thin surface layer over the modern South Australian dolomites.
14
R. W. FAIRBRIDGE, G. V. CHILINGAR AND H. J. BISSELL
It can be postulated that the rate of dolomite formation without catalysis is very slow under normal conditions, and that metastable minerals or mineral pairs form from supersaturated solutions. Organisms may well provide the catalysts. STABLE ISOTOPE DISTRIBUTION IN CARBONATES
Stable isotope distribution in carbonates is discussed by Egon T. Degens in Chapter 5. Calcite, aragonite, and dolomite are composed of four light elements: ( I ) carbon, (2) oxygen, (3) magnesium, and (4) calcium, all of which contain at least two stable isotopes. Most of the stable isotope fractionation in nature apparently is the result of exchange reactions occurring at or near equilibrium. Consequently, knowledge of isotope fractionation factors may reveal information on paleotemperatures, mode of formation, etc. Carbonates exhibit a range of about 12% in 13C/12C ratio. The heaviest carbonates occur in meteorites, whereas the lightest ones are associated with sulfur-evaporite domes (bacterial carbonates). As pointed out by Degens, a great number of marine organisms secrete a carbonate that is slightly enriched in 12C as compared to the value predicted by theory for a system in isotopic equilibrium (CRAIG, 1953; LOWENSTAM and EPSTEIN,1957; WILLIAMS and BARGHOORN, 1963). Thus, the fact that Recent limestones from many areas also show this slight enrichment in 12C content from the expected equilibrium value, suggests that these limestones are in part, at least, a product of life processes in the sea. As a result of even more 12C-enriched C02 contributions to the continental carbon dioxide system, the fresh-water carbonates may be distinguished from carbonates formed in a marine environment; hydrothermal carbonates in contrast are enriched in 13C. Precambrian marine carbonates are often enriched by a few permil (parts per mille) in 1% relative to the average S W of younger limestones, and thus are more like modern lacustrine carbonates. For air oxygen the ratio 1 6 0 / 1 7 0 / 1 8 0 = 99.759/0.0374/0.2039. The data, however, are generally reported in terms of lS0/160 ratio or P O , which is the permil deviation in 180/160 ratio relative to standard mean ocean water (SMOW). A range of about 4% in 1 8 0 / 1 6 0 is exhibited by carbonates; carbonates associated with certain continental evaporite deposits are the heaviest, whereas the igneous carbonatites are the lightest. The temperature dependence of oxygen isotopes allows paleotemperature determinations. Unfortunately, however, the original 1 * 0 / 1 6 0 record, as laid down during deposition, is diagenetically altered. Isotopic equilibration with the surrounding meteoric or connate waters, often intensified by higher temperature, results in an increase in 1 6 0 content of marine limestones and shell carbonates. The original 1 8 0 / 1 6 0 record, even of late Paleozoic carbonates, is preserved, however, under certain post-depositional environments.
INTRODUCTION
15
Isotope studies possibly would also contribute significantly to deciphering the origin of sedimentary dolomite. Dolomites, which precipitated in an aqueous environment at room temperature, should be heavier by ca. 6-10 permil in 1 8 0 over cogenetic calcite or aragonite (CLAYTON and EPSTEIN,1958; ENGELet al., 1958; EPSTEIN et al., 1964). Inasmuch as isotope data of Recent dolomite-calcite pairs from various localities show no significant difference between calcite and dolomite (EPSTEIN et al., 1964; DEGENS and EPSTEIN,1964) one may conclude that these dolomites did not precipitate from an aqueous solution. Thus, dolomite probably was derived by way of metasomatism of calcite, and dolomitization must have proceeded without significantly altering ls0/160 ratio of the precursor carbonate. DEGENS and EPSTEIN(1964) also found this to be true in the case of Paleozoic dolomites. The findings of Degens and Epstein are indeed a major step forward in our understanding of mechanism of dolomitization. The editors of this book, however, believe that further experimental work should be done in this field before reaching absolutely definite conclusions. Inasmuch as the stable isotopes of calcium differ in mass by up to 20% (4OC vs. W a ) , studies on calcium isotopes appear to be promising. There is also 5% variation in the 24Mg/26Mg ratios in dolomites (DAUGHTRY et al., 1962), which warrants further investigation. INFLUENCE OF PRESSURE AND TEMPERATURE ON LIMESTONES
The joint contribution (Chapter 6) by Bernard Mamet (of Brussels) and Micheline d’Albissin (of Paris) bears the unmistakable stamp of the classical metamorphic limestone studies that have been made over the last century in western Europe. Partly as a result of Mamet’s travels in America it has been possible to blend these data with the concepts developed in the New World by F. Adams, N. Bowen, D. Griggs, J. Handin, F. Turner, J. Verhoogen, and others. Several distinctive stages of alteration are recognized. First of all, simple diagenetic lithification occurs without temperature or pressure changes. Often there is merely a phase change with or without additional cementation and, sometimes, with recrystallization. The latter expression should be used if there are new grain boundaries and the initial fabrics are limited to ghost or palimpsest features. Mamet called the penecontemporaneously recrystallized rock “alpha sparite” and the subsequently altered rock “gamma sparite”. With increased load the pore spaces in loose calcitic mixtures disappear as a result of compaction, and there is a gradual increase in strength and stability. Precise quantitative data on the necessary loading to achieve a certain degree of compaction are lacking, in part because very small amounts of impurities can completely alter the crystallographic reactions, e.g., less than 2% MgO triggers recrystallization, whereas same amounts of clay inhibit it. Studies of microfossil walls, however, offer a fairly good yardstick for such pressure appraisal.
16
R. W. FAIRBRIDGE, G. V. CHILINGAR AND H. J. BISSELL
With the onset of regional, dynamometamorphic stress, calcite crystals become reoriented (with c-axes parallel to the principal stress). Plastic strain may be expressed by intracrystalline gliding, intercrystalline gliding and finally by recrystallization. The various methods of studying deformed fabrics are also discussed in Chapter 6: infra-red reflection spectroscopy, dilatometry, X-ray diffraction, corrosion patterns, thermoluminescence, etc. In contact metamorphism, Bowen’s thermal decarbonatization series gives the stages of alteration. If magnesium is present, which is usually the case, the series can be complete. In regional metamorphism, the metamorphic limestones react ultimately in the same manner as the surrounding silicate rocks, and consequently the established metamorphic facies series can be identified. An outstanding area of needed research is the progressive reaction of all types of carbonate sediments to simple basin compaction to the equivalent overburden load of 30,000 ft.
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
In Chapter 7, John M. Hunt discusses the origin of petroleum in carbonate rocks. This chapter is a very important contribution, because it has been frequently assumed that petroleum does not originate in carbonate rocks. Thorough studies of both Recent and ancient carbonates, however, show that the amounts of hydrocarbons present in them are comparable to those in clay sediments. Hunt pointed out, nevertheless, that there are certain basic differences in the source and types of organic matter deposited with carbonates as compared to shales. In addition, the rapid lithification of carbonate rocks, as compared to the slow compaction of argillaceous sediments, leads to different conditions of migration. Migration paths are developed through fissures, fractures, and solution channels. Approximately 87 billion barrels of oil are now known to be present in carbonate rocks in major oil fields outside the Soviet Union and other east European countries. Inasmuch as some of these reservoirs are surrounded by carbonate rocks, a reasonable assumption is that carbonates can also be the mother rocks of petroleum. The close association of source and reservoir beds in carbonates, in addition to the frequent presence of impermeable evaporite cap-rocks, probably results in a more efficient process of oil accumulation in carbonate rocks than in sand-shale sequences. Evidences of molecular migration within carbonate source rocks are quite numerous and convincing. There is a possibility for the catalytic generation of hydrocarbons in carbonate rocks, because small amounts of clay are present in many of these rocks. The conversion of organic matter to hydrocarbons in pure carbonates is a thermal process; hydrocarbons could then migrate along the solution and fracture zones.
INTRODUCTION
17
As pointed out by Hunt, this suggests that somewhat greater depths of burial and longer periods of time are required to generate oil in carbonates as compared to clays.
TECHNIQUES OF EXAMINING A N D ANALYZING CARBONATE SKELETONS, MINERALS AND ROCKS
Chapter 8 is devoted to the techniques usually employed for examining and analyzing carbonate skeletons, minerals and rocks. It is the joint work of Karl H. Wolf, A. J. Easton and S. St. J. Warne. Some of these techniques are traditional; others are rather new. Both quick field tests and the more quantitatively precise laboratory tests are described, but space requirements limit detailed treatment to those procedures that seemed to the authors to be the most convenient and appropriate. The basic technique to assist hand lens and binocular examination is the etched surface, which may be produced even under field conditions with a variety of weak acids. This is ideal for a preliminary appraisal of the microfacies, the texture and structure. To distinguish further, for example, between faecal, bahamite and algal pellets, between “open-space” sparite and recrystallization sparite, etc., thin-sections are needed. Even these can be prepared in a field camp with a little ingenuity. Another helpful field procedure, that may also be used in the laboratory, is that of staining. It is essentially limited to grain sizes larger than 0.01 mm. The same is true of spot tests. Both well-lithified and unconsolidated material can also be studied for textures and structures by acetate peel techniques. These are particularly helpful both for the study and easy storage of records of microfacies. These methods also can be applied both in the laboratory and in the field. With the accumulation of large volumes of data, special statistical methods and graphic presentation have been developed. Study of the associated insoluble minerals is often helpful, but care must be taken not to alter them seriously during the separation process (especially in the case of clays). The carbonate minerals themselves are often difficult to distinguish from one another in thin sections. Determination of the refractive index by oil immersion is commonly employed, but overlaps occur in the isomorphous series and hence staining, chromatography, etc., may be used. The universal stage microscope is also helpful. In recent years the electron microscope is rapidly gaining in popularity (with its increasing availability); surface textures of fine-grained carbonates, particularly the organogenic ones, are remarkably characteristic. X-ray radiography is helpful when dealing with mixed terrigenous lithologies. Great care must be taken with aragonite, because it tends to invert to calcite under grinding or during preparation of thin-sections.
18
R. W. FAIRBRIDGE, G. V. CHILINGAR AND H. J. BISSELL
Methods of chemical analysis have also been presented in Chapter 8 in some detail for the various carbonates as well as for some of the related trace elements. Traditional methods of wet analysis have of late been partially replaced by the use of the spectrophotometric instruments and by the flame photometer. Differential thermal analysis and X-ray diffraction are now standard procedures, and their particular application to the various carbonates are treated in detail in this book. Thermoluminescence is also a phenomenon that has been applied to carbonate study in recent years; it has attracted considerable attention with various objectives in mind, both analytical and paleoecological. Further basic studies, however, are still required in this field. Of invaluable use in determining the rates of sedimentation and the recent ecologic history of carbonate rocks is Urey’s method of 1% age determinations. Many refinements have been added over the last fifteen years, and many anomalies and confusing aspects have been ironed out. The half life of 14C essentially limits the method to less than 50,000 years; however, encouraging research, work on carbonate shells has been made in recent years with uranium-helium, protoactinium and thorium methods that may extend the datable ranges to several million years. Isotope studies have also been widely employed in determining paleotemperatures (1*0/160), in distinguishing organic from inorganic carbonates (13C/W), and for a number of other purposes.
PROPERTIES AND USES OF THE CARBONATES
The economic aspects and practical uses of the carbonates, here discussed in Chapter 9 by Dr. F. R. Siegel, are numerous. Inasmuch as bulk supplies, especially of limestone and dolomite, are often required, accessibility and short transport routes from consumers are of the highest importance. In some parts of the world this is no problem, but in others (notably the Precambrian shield and volcanic regions) there may be serious deficiencies. Annual consumption figures for limestone in a country such as the United States are constantly rising, and indeed may be taken as an approximate index of the gross national product. This is especially true if the year to year figures are seen on a tonnage basis rather than on the sliding scale of a gradually inflating currency. For example, in 1964 crushed stone used in U.S.A. exceeded 700 million tons as compared with less than 450 million tons in 1954. Lime production in 1964 was 19 million tons against 8 million tons in 1954. Portland cement output was 360 million barrels in 1964 against 290 million barrels in 1954. Some 100 uses are listed for limestone, dolomite and marble (Table XI11 in Chapter 9). Some are employed directly as for building stone (known technically in the U.S.A. as “dimension stone”); others indirectly as in the chemical industry
INTRODUCTION
19
(e.g., “whiting”, see over 70 uses listed in Table XIV in Chapter 9), glass manufacture, or in sugar refining. Other carbonate minerals are not found in large rock-forming deposits as is the calcium-magnesium group; they are mainly utilized as metal ores and in the chemical industry. These include rhodochrosite, an ore of manganese, also used as a pigment “manganese white”; siderite, an iron ore; smithsonite, a zinc ore and pharmaceutical; witherite, a barium ore, also used in sugar refining, as a rat poison, in paints, and in glass and paper industries; strontianite, a strontium ore, also used in sugar refining, in paints, glass and in pyrotechnics; cerussite, a lead ore, also used in paints, for putty and in “leaded” paper; malachite and azurite, copper ores and ornamental stones such as vases and table tops; and trona, a sodium ore, used in the glass, paper, soap and other chemical industries. Modern research is constantly opening new areas of use for the carbonates. The new “oxygen process” for steel smelting uses twelve times more limestone than do conventional refractory methods. Consumption, even of the simple crushed rock, will rise inevitably. A natural by-product of limestone country is the geomorphic phenomenon, the “karst” landscapes and caverns. Whereas the waterless land surface may be poor for agriculture, it is sometimes more than offset by the valuable tourist attractions of the caves, with their stalactites and stalagmites, underground streams and speleological interests. Karst systems (if adequately sealed) also offer a potential for underground storage of gasoline, etc. Another group of limestone geomorphic phenomena of very considerable tourist value are the coral reefs, and the related island-life charms extending across the tropical Pacific and Indian Oceans. The rather minor, though more accessible, examples in the Atlantic include those in Florida, the Bahamas and West Indies. REFERENCES
In reviewing various chapters in this book, in many instances the editors quoted the same authors whose names appear in the reference lists of particular chapters; these references are not repeated here.
ALEKIN,0. A., 1953. Principles of Hydrochemistry. Gidrometeoizdat, Leningrad, 296 pp. ATWATER, G. I., 1965. American Association of Petroleum Geologists, Distinguished Lecture Series. Based on: ATWATER, G. I. and MILLER,E. E., 1965. The effect of decrease in porosity with depth on future development of oil and gas reserves in South Louisiana. 27 pp., unpublished. BARON,G. et FAVRE, J., 1958. ktat actuel des recherches en direction de la synthese de la dolomie. Rev. Znst. Franc. PJtroIe Ann. Combust. Liquides, 13(7-8): 1061-1085. CHILINOAR, G. V., 1956a. Solubility of calcite, dolomite, and magnesite, and mixtures of these carbonates. Bull. Am. Assoc. Petrol. Geologists, 40: 2770-2113. CMLINGAR, G. V., 3956b. Note on direct precipitation of dolomite out of sea water. Compass, 34: 29-34. CIIILINOAR, G. V., 1956c. Relationship between Ca/Mg ratio and geologic age. Bull. Am. Assoc. Petrol. Geologists, 40(9): 2256-2266.
20
R. W. FAIRBRIDGE, G. V. CHILINGAR AND H. J. BISSELL
CHILINGAR, G. V., 1956d. Abundance of carbonate rocks in European U.S.S.R.: a summary. Bull. Am. Assoc. Petrol. Geologists, 40 (8): 2022-2023. CHILINGAR, G. V. and BISSELL,H. J., 1961. Dolomitization by seepage refluxion (Discussion). Bull. Am. Assoc. Petrol. Geologists, 45(5): 679-681, CHILINGAR, G. V. and BISSELL,H. J., 1963a. Formation of dolomite in sulfate4hloride solutions. J. Sediment. Petrol., 33: 801-803. CHILINGAR, G. V. and BISSELL, H. J., 1963b. Note on possible reason for scarcity of calcareous skeletons of invertebrates in Precambrian formations. J. Paleontol., 37: 942-943. CRICKMAY, G. W., 1945. Petrography of limestones. In: H. S. LADDand J. E. HOFFMEISTBR (Editors), Geology of Lau, Fiji-Bernice P. Bishop Museum Bull., 181 : 21 1-250. DOIGOV,G. I., 1955. Sobinskiye Ozera. Trudy Vses. Gidrobiol. Obshchestva Akad. Nauk S.S.S.R., 6: 193-204. EREMENKO, N. A. (Editor), 1960. PetroleumGeology (Handbook), I . PrinciplesofPetroleumGeology. Gostoptekhizdat, Moscow, 592 pp. FAIRBRIDGE, R. W., 1957. The dolomite question. In: R. J. LEBLANC and J. G. BREEDING (Editors), Regional Aspects of Carbonate Deposition-Soc. Econ. Paleontologists Mineralogists, Spec. Publ., 5 : 125-178. FAIRBRIDGE, R. W., 1964. The importance of limestone and its Ca/Mg content to paleoclimatology. In: A. E. M. NAIRN(Editor), Problems in Paleoclirnatology. Wiley, New York, N.Y., pp.431-530. S. I., IVANOV, M. V. and LYALIKOVA, N. N., 1963. Introduction to Geological MicroKUZNETSOV, biology. McGraw-Hill, New York, N.Y., 252 pp. G. V. (Editors), 1966. Diagenesis in Sediments. Elsevier, AmsterLARSEN,G. and CHILINGAR, dam. (In press.) NAGY,B., 1960. Review of the chromatographic “plate” theory with reference to fluid flow in rocks and sediments. Geochim. Cosmochim. Acta, 19: 289-296. PRAY,L. C. and MURRAY, R. C., 1965. Dolornitization and Limestone Diagenesis ( A Symposium) -Soc. Econ. Paleontologists Mineralogists, Spec. Publ., 13: 180 pp. G. V. and ROBERTSON RIEKE111, H. H., CHILINGAR, JR., J. O., 1964. High-pressure (up to 500,000 psi) compaction studies on various clays. Intern. Geol. Congr., 22nd, New Delhi, 1964. (In press.) RONOV,A. B., 1964. General tendency in the evolution of composition of earth crust, ocean, and atmosphere. Geokhimiya, 1964(8): 715-743. RUKHIN, L. B., 1961. Principles of Lithotogy, 2nd ed. Gostoptekhizdat, Leningrad, 779 pp. (In Russian.) JR. J. W., and CRICKMAY, SANDERS G. W., 1945. Chemical composition of limestones. In: H. S. LADDand J. E. HOFFMEISTER (Editors), Geology of Lau, Fii-Bernice P . Bishop Museum Bull., 181: 251-259. SIEGEL,F. R., 1961. Factors influencing the precipitation of dolomitic carbonates. State Geol. Surv, Kansas, Bull., 152(5): 127-158. SVERDRLJP, H. U., JOHNSON, M. W. and FLEMING, R. H., 1962. The Oceans, Their Physics, Chemistry, and General Biology, 4th ed. Prentice-Hall, New York, N.Y., 1087 pp. J. W., 1964. Modern carbonate sediments of southern Florida, TAFT, W. H. and HARBAUGH, Bahamas, and EspIritu Santo Island, Baja California: a comparison of their mineralogy and chemistry. Stanford Univ. Publ., Univ. Ser., Geol. Sci., 8(2): 133 pp. VALYASHKO, M. G., 1962. Geochemical Regularities in the Formation of Potassium Salt Deposits. Izd. Moskov. Univ., 397 pp. VINOGRADOV, A. P., 1953. The Elementary Chemical Composition of Marine Organisms. Sears Foundation for Marine Research, Yale Univ., New Haven, Conn., Mem., 2: 647 pp. J. M., 1959. Compaction of sediments. Bull. Am. Assoc. Petrol. Geologists, 43(2): 273-310. WELLER, YANAT’EVA, 0. K., 1950. The solubility of dolomite in aqueous salt solutions. Izv. Sektora Fiz. Khim. Analiza, Inst. Obshch. Neorgan. Khim., Akad. Nauk S.S.S.R.,20: 252-268. YANAT’EVA, 0. K., 1954. About physical-chemical characteristic of some carbonate rocks. Dokl. Akad. Nauk S.S.S.R.,96(4): 717-719. YANAT’EVA, 0.K., 1957. On the solubility polytherm of the system (CaCOs MgSO4 $ CaS04 MgCOs) - HzO. Proc. Acad. Sci. U.S.S.R.(Chem.Sect., English Transl.), 1957: 155-151.
+
+
21
INTRODUCTION
APPENDIX A COEFFICIENTSFOR CONVERTING mg/l TO rng-equiv./l
Ions
1
(rng/l
Equivalent weight
Coefficient
20.035 (20) 12.16 22.997 (23) 18.03 30.0 48.03 (48) 35.476 (35.5) 61.0 46.0 62.0 17.0
0.0499 0.0822 0.0435 0.0554 0.0333 0.0208 0.0282 0.0164 0.0217 0.0161 0.059
See also EREMENKO (1960).
-
COEFFICIENT
= mg-equiv./l)I
Chapter 2 ELEMENTAL COMPOSITION OF CARBONATE SKELETONS, MINERALS, AND SEDIMENTS K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES Department of Geology, The Australian National University, Canberra, A.C. T. (Australia)' Department of Petroleum Engineering, University of Southern California, Los Angeles, Cal$ (U.S.A.) Department of Geology, University of Toronto, Toronto, Ont. (Canada)
SUMMARY
Emphasis is laid upon the basic chemical, organic, and inorganic principles that determine the composition of carbonates. Elemental compositions vary considerably depending on numerous primary and secondary factors. Their significance has been documented by selected published examples. The practical applicability of elemental analyses of carbonates is stressed, and some case histories provide evidence that the chemical make-up of both the carbonates and associated non-carbonate components can be useful indicators of the original environmental conditions. It is hoped that data compiled here are sufficient to stimulate further research in this interesting field of sediment geochemistry.
INTRODUCTION
Carbonate minerals and rocks form in nature over a wide range of environmental conditions and their composition is controlled largely by their mode of genesis. In addition to constituting approximately 10-1 5 % of the sedimentary deposits, carbonates occur also in certain varieties of igneous and metamorphic rocks. In general, therefore, carbonates can be divided into high- and low-temperature types. The present contribution, however, deals almost exclusively with the low-temperature and low-pressure carbonate minerals and rocks. Further, inasmuch as a comprehensive summary of many of the aspects related to sedimentary carbonates has been presented recently by a number of workers such as REVELLE and FAIRBRIDGE (1957), and GRAF (1960), the authors confined themselves to the discussion of selected fields covering only some of the many facets of the elemental composition
Present address: Department of Geology, Oregon State University, Corvallis, Ore. (U.S.A.).
24
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
of carbonates. A summary of the absolute values of chemical elements appears to be premature in view of the rapid advances in both compositional data and concepts of genetic mechanisms. Hence, no pretense is made of completeness and much of the information presented here is of necessity sketchy and superficial. Where a choice has had to be made between brief citations, or more complete coverage of fewer examples, the authors have favored the policy of reference to as many different publications as space permitted. Numerous gaps are only too apparent in the present state of our knowledge. For example, RONOVand KORZINA (1960) pointed out the gap in our knowledge between highly concentrated mineral deposits on the one hand, and the dispersed trace minerals and trace elements on the other.
FACTORS AND PROCESSES DETERMINING THE ELEMENTAL COMPOSITION OF CARBONATES
Some details of materials, conditions, and processes that control the composition of carbonate minerals, skeletons and rocks are given in other chapters. By way of introduction, and to emphasize the complexity of inter-relationships, however, some of the factors and processes that are considered in other chapters are listed as follows: Physicochemicalfactors (I) (2) (3) (4) (5)
(6) (7)
(8) (9)
Composition of solution (type of ions present). Concentration of ions present. Ionic potential (= property of ions). pH (= property of solutions). Eh (= property of both solutions and ions). Temperature and pressure. Rate of reactions. Solubility of the various possible compounds that can form. Absolving property of water medium and other fluids (GOTO,1961).
Organic influences (I) Direct metabolic processes (e.g., processes which control composition of both carbonate skeletons and organic matrix). (2) Indirect influences by changing environment (e.g., metdbolic processes of animals and plants may change pH, Eh, and ion-concentration of water medium). (3) Biotic reworking (e.g., mud-eater may cause chemical alteration of carbonate sediments in digestive system before excretion as fecal pellets occurs). (4) Bacterial processes (although strictly referrable to items 1 and 2 above,
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
25
solution, deposition, and transformation of carbonates and solutions by Bacteria is a sufficiently important topic to warrant separate mention), e.g., post-humous decomposition of organic matter (gases, fluids, and ions are liberated to the surrounding environment as a result of decomposition), sulfate reduction and so on. Inorganic processes
( I ) Precipitation (e.g., deposition of aragonite, low-Mg calcite, etc., by evaporation). (2) Solution (e.g., selective removal of more soluble carbonates). (3) Leaching (e.g., selective removal of ions from carbonate minerals and skeletons without actual solution). ( 4 ) Oxidation and reduction. (5) Adsorption-diffusion-absorption (e.g., differential uptake of ions by clay minerals and both living and dead organic matrix). (6) Replacement (e.g., replacement of carbonates by carbonates or by noncarbonates). (7) “Recrystallization” (a number of processes included here can change the composition of the carbonates). (8) Extraneous contribution (e.g., terrigenous, volcanic, and cosmogegcpus). Two important factors have to be taken in consideration in all discussions on the chemical composition of sediments, namely, first, the limitations of the methods and instruments employed, and second, the “human” factors involved in collecting samples, and others (LAMARand THOMPSON, 1956). Numerous sensitive stability ranges and geochemical thresholds clearly control the equilibria involved in carbonate-rock formation. Numerous examples of complete alteration and many reversible reactions are well documented in the literature. Probably even more serious at the present time is our lack of knowledge of the relationships between organogenic and purely physical processes in carbonaterock formation. Organic processes undoubtedly predominate in providing the raw materials from which the bulk of Phanerozoic (post-Precambrian) limestones have formed. The course of their subsequent diagenesis has largely depended on physical processes. Many direct and indirect inter-relationships undoubtedly occur and will be the subject of much research in future years. It is hoped that this partial compilation of ideas will assist both assessment of the present state of our knowledge and the research that will advance our understanding further.
ELEMENTAL COMPOSITION OF CARBONATE SKELETONS, MINERALS, AND ROCKS
In a general way, the numerous chemical components of carbonates occur in what has been usually termed, major, minor, and trace quantities. Where cations can
26
K. H.
WOLF, G.
V. CHILINGAR AND F. W. BEALES
form a partial or complete solid solution, the ionic species can be expected to occur in either major or minor quantities, or as minute traces. Considering particular solid solution series, it has been found that elements occurring as traces under some conditions, will be present as minor or even major components under other physicochemical or biochemical influences. On the other hand, certain elements never occur in concentrations beyond that of minute traces in carbonate skeletons, minerals, and rocks due to numerous geological and chemical reasons as illustrated here. The writers refrained from setting precise boundaries between the major, minor, and trace elements as they would serve no purpose in the present discussions, especially in view of the uncertain chemical affinities of the components in many cases. The chemistry of sedimentary carbonates is in general divisible into the following aspects: ( I ) isomorphism (= solid solution) of carbonate minerals, (2) minor and trace elements in carbonate minerals, (3) “fluid inclusions” in carbonates, and (4) non-carbonate components in carbonate sediments. Each aspect is considered briefly as given below. Isomorphism of carbonate minerals
Complete low-temperature isomorphous substitution of one cation by another is possible in the following cases: - rhodochrosite (MnCOs) calcite (CaC03) dolomite (CaMg(CO3)z) - ankerite (CaFe(CO3)z) - siderite (FeC03) magnesite (MgC03) rhodochrosite (MnC03) - siderite (FeC03) strontianite (SrC03) - witherite (BaC03); isomorphous only in artificial material. High-temperature solid solutions (not further considered here) are discussed in the following references (among others): (1 963) for ROSENBERG MgC03-FeCO3, and MnC03-FeC03 ROSENBERG (1 963) for CaC03-FeC03 HARKER and TUTTLE ( 1 955) for CaC03-MgC03 GOLDSMITH (1959) for CaC03-MgC03, CaC03-MnC03, and CaC03FeC03 CaC03-MgC03-FeC03 GOLDSMITH et al. (1 962) for CHANC(1 963) for BaC03-SrC03, SrC03-CaC03, and BaC03CaC03 GOLDSMITH et al.( 1955) for MgC03-CaC03 CHAVE (1 952) for CaCOs-CaMg(CO3)z (of low-temperature origin) HOLLAND et al.( 1963) for Zn and Mn coprecipitated with calcite; and Sr content of calcite and other carbonates.
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
27
Reference can also be made to general publications such as those by GRAF and LAMAR (1955), GRAF(1960), GOTO(1961), and DEER et al. (1962). Rare carbonate minerals are not discussed in this chapter although they most certainly will be of definite interest in future petrologic studies: in particular those concerning diagenesis. ALDERMAN (1959), for example, pointed out that huntite (CaMg3 (C03)4), which usually forms as a weathering product of dolomite and magnesite, may prove to be more widespread than is generally assumed. Minor and trace elements in carbonate minerals
According to DEERet al. (1962), the following elements, in addition to the major ones given in the formulae above, have been recorded: (1) calcite-Mg, Mn, Fez+, Sr, Ba, Co, Zn; (2) aragonite-Sr, Pb, Ba, Mg(?), Mn (?); (3) dolomite-Fe2+, Mn, Pb, Co, Ba, Zn, Ca, replacing Mg; less commonly Mn, FeyPb, and Mg substituting for Ca; ( 4 ) ankerite-Fez+, Mn; (5) siderite-Mn, Mg, Ca, Zn, Co; (6) magnesite-Fez+, Ca, Mn, Ni, Co, Zn; (7) rhodochrosite-Ca, Fez+, Mg, Zn, Co, Cd; (8) strontianite-Ca; and (9) witherite-Ca, Mg. It should be noted, however, that many of the above minor and/or trace elements occur in high-temperature carbonate minerals. Probably, future research will show presence of other elements in these minerals. According to LOGVINENKO and KOSMACHEV (1961), mainly binary series of isomorphism are described in the literature, whereas information on polycomponent systems such as (Fe, Ca, Mg, Mn)C03 are scarce or lacking. In many cases, the minerals have been identified by optical, X-ray, thermal, staining, and other methods as ones of simple composition, and none of the other elements were detected in spite of their presence in comparatively large amounts. In this regard the binary nomenclature (e.g., ferroan calcite, breunnerite) is misleading. For example, LOGVINENKO and KOSMACHEV (1961) determined the composition of diagenetic carbonate concretions to be ( F ~ s z . z ~ - s s . ~Ca7.39-12.96, z, Mnz.45-3.10, Mg0.34-5.26) CO3. (A similar occurrence has been quoted in the chapter on techniques of analyzing carbonate skeletons, minerals, and rocks -WOLF et al., 1967.)
Fluid inclusions in carbonates Inter- and intra-crystalline fluid inclusions in calcite and dolomite minerals are mentioned by LAMAR and SHRODE (1953) and SHOJIand FOLK(1964). The former two investigators examined water-soluble .salts in carbonate rocks and concluded that “much of the calcium and sulfate (excluding calcium dissolved from the calcite and dolomite) probably occurs as intergranular solid calcium sulfate with magnesium sulfate possibly occurring in the same manner”. As thin-section and decrepitation studies suggest, however, “the sodium, potassium, and chlorides,
28
K. H.
WOLF, G.
V. CHILINGAR AND F. W. BEALES
together with some calcium, magnesium, and sulfate, are probably present primarily in solution in intragranular fluid inclusions”. SHOJIand FOLK(1964) found fluid inclusions in calcite during electronmicroscopic investigations of carbonates. The calcites are often spongy due to densely crowded bubbles. The above authors suggested that the inclusion-rich calcite formed in environments that lacked clay-sized carbonate and where the sea water was relatively clean. The sponginess of the calcite may affect dolomitization. Influences on other diagenetic processes by these fluid inclusions may also be expected. As to what extent these fluids can be used in environmental reconstructions remains to be determined by future research (WEBER,1964b). Non-carbonate components in carbonate sediments
Non-carbonate components in calcareous sediments are inorganic or organic in composition. The sum total of organic matter from diverse sources has a considerable influence on the cation composition of sediments. The non-calcareous material is either syngenetic, diagenetic or epigenetic in origin according to one consideration (see CHILINGAR et al., 1967) and either detrital or authigenic from another view-point. When attempting to separate the non-carbonate from the carbonate fraction, it is significant to consider that not all non-carbonate fractions are “insoluble” (see WOLFet al., 1966). GRAF(1960) gave a list of authigenic minerals that have been reported from carbonate sediments. This list included fluorite, celestite, zeolites, goethite, barite, clay minerals, phosphate, pyrolusite, gypsum, feldspar, micas, quartz, sphene, rutile, glauconite-chlorite, tourmaline, pyrite-marcasite, rare carbonate minerals, and a host of others, that can form at the surface or within the carbonate sediments. In general, one of the most significant and widespread contaminants of sedimentary carbonates is the clay fraction. The adsorption and ion-exchange ability of the clays makes them valuable as environmental indicators that may assist in distinguishing between fresh-water and marine limestones. DEGENS et al. (1958) showed that the clay fraction of these two types of calcareous sediments have significant mean differences in boron and gallium contents; and that the interpretations as to whether they are fresh-water or marine deposits agree in 80% of the cases examined, where previous environmental reconstructions were based on fossil evidence. WALKER (1964) has done some similar work on the boron content of clays. GULYAEVA and ITKINA (1962) found that clays and argillites of fresh-water facies differ from those of marine deposits in having lower halogen contents and low CI/Br and Br/l ratios, as given in Table I. To what extent the observations on the halogens apply to clays derived from carbonate sediments remains to be seen. Both skeletal and inorganieally formed carbonate sediments commonly contain organic matter, in particular in the early stages of sedimentation. In both
29
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
TABLE I RATIOS OF
Br/I
AND
CI/Br I N SOME MARINE AND FRESH-WATER CLAYS
(After GULYAEVA and ITKINA,1962) Marine clays
Br/I CI/Br
8.8- 16.3 75 -170
Organic-rich marine clays
5- 6 45-64
Fresh-wafer clays ~-
~
2.2-2.7 5. I
living and post-mortem stages, the organic matter controls to a marked degree both minor and trace elements in the bulk composition of carbonate skeletons and rocks, as mentioned above. For example, GOLDSCHMIDT (1 937), GOLDSCHMIDT et al. (1948), and KRAUSKOPF (1955) stated that carbonate sediments rich in organic matter may be enriched in Mo, V, Ni, Pb, Cu, Ag, As, Ge, I, and Br (see also GRAF,1960). KRAUSKOPF (1955) suggested that Pb, Zn, Ni, and Cu may react with H2S liberated from decaying organic matter and precipitate as sulfides. Similar correlations exist between inorganic components and trace elements. For instance, sediments containing manganese oxide have been known to be enriched in Co, Mo, and Ba; and phosphatic limestones often contain F and CI in the structure of the phosphate minerals. K. G. BELL(1 963) stated that carbonate rocks that are composed wholly of carbonate minerals and contain only traces of other constituents generally have about 0.0001 %, or less, of syngenetically precipitated uranium. The impure carbonates, however, may contain 0.OOOX-O.OOX% of' uranium. This element is associated with phosphatic, organic and detrital components mainly; and, according to K. G . Bell, no appreciable amounts of uranium can be expected in the carbonate fraction itself. Both the fluid inclusions and numerous types of non-carbonate constituents mentioned above make it extremely difficult to determine the form of occurrence of the major, minor and trace elements present in skeletons, minerals and rocks. Thus, in many studies elaborate techniques had to be devised to achieve a separation of the different fractions. The chemical data given in Table I1 and 111 can, therefore, be used only as general guides to the elemental composition of carbonates; much more research is required before the actual distribution of all elements can be demonstrated and predicted.
TABLE I1 TRACE-ELEMENT COMPOSITIONOF CARBONATEAND NON-CARBONATECONSTIWENISI
Ag
Limestones
P--G 4 p.p.m.
Dolomites
PG
“Carbonates”
P--G 20 p.p.m.
“Insolubles” Clays “Heavies” Organic matter Bitumen Algae Phaeophyceae
Rhodophyceae
Chlorophyceae
Corallinaceae
A1
As
B
Ba
P-G
P--G
PG
p.p.m. P--G
P--Gp--G
p.p.m. F - G
Au
P--G 15 p.p.m.
65 p.p.m.
0.009
p.p.m.
S-FM
1.2.10-6
g/g d.m. P--v
Bi
s-V,FM
2.10-8
g/g d.m.
6,000
p.p.m. P--G p--G P--G
C
Ca
P--G 15 p.p.m.
2,000
8,000
P--G 3 p.p.m.
P--G
p--G P-G
p.p.m. P--G
Br P--G 10 p.p.m.
200 p.p.m. 10,000
0.5 p.p.m.
P--v
Be
x
8
P-G
“Q
p-v
P--v
P-v
9
P-v
5
10 mgl 100 g d.m.
s-v
p-v
P--v
0
1.m.
d.m.
2
P--v
p-v
$ger
1.2 mg/ 100 g d.m.
s-v
CaO of ash P-V
1.m.
d.m.
CaO of ash
2 tl w
P--v
s-v
0.08 mg/ 1,OOo g
d.m.
0.044%
0.7%
0.02%
1.m.
43%
28%
p-v
46% d.m.
64%
89 %
P-v
60 %
CaO of ash h-V,K
99.3 %
CaC03
$
5,
2
!F
::
'a
n
1
>
> I n
> I n
> I n
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
a-
31X
nov
1
x
h
>1-4 s x nov
l?G
>-
x E koa
31
0
c
m
x 5
.-M ul .0
a2 *
8
*
h
32
$
4
Q 4 rq
3
T
i T
c
+
0,
r,
1 3a % cv,
?,
>
x > O mI q o
Fj
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
0
(r
> I w > I
5
v)
I
>
A
I
>
1
> c
E
E
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
9,
4
4
$
G
-
3
r 3
L
3
a
3
00
I I
an
I
a
0
E
> aI
%>
k %k
0
i i > l
a
> I n
2
s
> I a
F 3
33
0
e
of
x 0
0
v)
'a ._ 0
Y
0
e *
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
E
I?
0 % & -
a
I
>
a
c
Lass
>XkL,1
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
194 no a
r
Ew4 3: 194 a0 a
*w
m
koa
x now
x
>I?€ a0a
Lox
E >p
35
36
I
9
x
>IA
Ms o uE
I
>
f I
>
9
x
E 0 ; IIA cri v)
> I
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
VYOU
>I x d.
I
VY
>
I
v)
>
v)
> I
> I
f
I
c
0
u n
I
> I e.
nI
>
> nI
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
00 & n182 -
I
a
0
I
P
0
i n
> nI
37
o\
f a C 0
F
0
.M m .0
Y
Y
;4"
38
x
E.*
ks 2
W p
K. H. WOLF, G . V. CHILINGAR AND F. W. BEALES
v)
> I
Arthropoda Trilobita Crustacea
P--v 7.7 % d.m.
Echinodermata
s-v 0.0016% 1.m. s-v
Echinoidea
s-v 0.52 % 1.m.
0.05 %
P-V
P - G 25 p.p.m.
3
E
h-V 7 10-5% d. wt.
Crinoidea Annelida
d
8 z s-v 6.73 % d.m.
-
Mg
Limestones Dolomites “Carbonates” “Insolubles” Clays “Heavies” Organic matter Footnote is given on p.49
s-v 0.651 % d.m.
s-v 2.22 % KzOd.m.
s-v
v)
m
8
5
~~
Mn
Mo
P--G
P--G 22 p.p.m.
3,200 p.p.rn. p--G 4,100 p.p.m. P - G 2,800 p.p.m.
p--G 1.2 p.p.m. P--G 70 p.p.m.
P--G
B 5 F 0 0
s-v
d.m.
m
G
N
Na
P--G 150 p.p.m. P--G 240 p.p.m.
P - G
Nd
Ni P--G 70 p.p.m.
P--G 14 p.p.m. P--G 100 p.p.m. P--G 190 p.p.m.
P
Pb
P--G 100 p.p.m. P--G 8 p.p.m.
Pr
Ra P--B 58 glg
. 10-14
2
ga 4 cl
*
E 2
sE
P--G 200 p.p.m. P--G
P--G
P--G
P--G w
\o
TABLE I1 (continued) Mg
Mn
Mo
N
Na
Nd
Bitumen p-V,FM
Algae Phaeophyceae
Rhodophyceae
Chlorophyceae
Corallinaceae
Rryozoa
P V 15% MgO of ash P--v 15% MgO of ash P V 9.7% MgO of ash p-V,G II % MgO of ash h-V,G 11%
Protozoa Foraminifera "Globigerina ooze"
P--v
1.0 * 10-6
MgC03 wt.
P--v 0.015% d.m.
g/g d.m.
P--v 4.8 % d.m.
P--v 0.036% d.m.
P--v 6.6 % d.m.
P-V 0.008 "/, d.m.
P-v 5.6 d.m.
p-V,G 0.02% d.m.
P--v
p-V,G,S, p-H,G,S BT 0.1 % >25 mol% p-G 2,600 p.p.m.
Ni
P-G
P-V
p-v P--v 5.9 % PZo5 of ash P--v 46.5 % pzos of ash P--v 4.8 % pzos of ash h-V,G
P--v 34 % NazO of ash P--v 27 % NazO of ash
P-v
22.2 % NazO of ash P--v 2.8 % Nan0 of ash
0.5%
P --G
P-G 60 p.p.m.
Pr
Ra
p-v
p-v
F
r
p-G 0.8 p.p.m.
CadPWz wt. h-G 8.5% p-V CadPO& wt.
P--s C u > Ni> Pb> Co> Zn> C d > Mg. It appears, that the stability decreases as the basicity of the metal increases. Schubert also reported that for alkaline earth metals the order generally i s Z n s Mg, Ca> Sr> Ba> Ra, where position of Mg is often irregular. For certain tervalent metal ioas the sequence is often as follows: TI> Fe> G a > In> A12 Cr> Sc> rare earths. For the rare earths the order is Y > Sm> N d > Pr> La, again in the order of increasing basicity. In the case of group of divalent metal cations of the first transition series, the stability of complexes increases to a maximum (at copper) and then decreases: M n < Fe< C o < Ni< C u > Zn. It is of importance to remember that stability relationships may vary. For example, Mn2+ ions form stronger complexes with oxygen-type ligands, and Co2+, with nitrogen-type ligands; these differences are even more pronounced for c03+and Mn3+ ions 1954). (SCHUBERT, GOLDBERG (1957) mentioned that the fractionation factors (concentration in organism/concentration in sea water ratio) for sponges, for example, are as follows: Cu, 1,400; Ni, 420; Co, 50; Mg, 0.07; and Ca, 3.5. Biochemical fractionation can lead to an extensive depletion of some elements in the surrounding sea water as has been reported already for strontium in waters near coral reefs (SIEGEL,1960), and during extensive radio-yttrium ion concentration by red Algae and diatoms. Regarding the uptake of trace elements in connection with particulate matter by members of the marine biosphere, GOLDBERG (1957) mentioned that “these particles can enter the marine biosphere via the filter-feeding organisms and their predators, as well as by direct transfer through adhesion to the outer surfaces of plants and animals”. Because all these substances, except calcium carbonate, can exist as colloidally dispersed particles, it may be expected that the adsorbed ions with charges opposite to those of the colloidal particles will accompany them. LEHNINGER (1950) stated that the biological specificity of metal ions for such organic substances as proteins depends on: (I) the mass of the ions, (2) ionic charge, (3) ionic radius, (4) oxidation-reduction potentials of the ions, and (5) availability and chemical state of elements, among others.
74
K. H. WOLF, G. V. CHlLlNGAR AND F. W. BEALES
Certain enzymes have been found to contain Mn and facilitate the precipitation of calcium phosphate. INGERSON (1962) suggested that similar enzymes in lime-secreting organisms may be active in the deposition of calcium carbonate and possibly even of dolomite. In pursuing this problem the active metal in the enzymes should be of particular interest. INGERSON (1962) suggested that, although the available information is extremely scarce, the work of VINOGRADOV (1953) and others shows that certain groups of organisms are characterized by relatively high contents of certain elements. If high concentrations of particular elements, that are known not to precipitate inorganically, are present in carbonate sediments, it may indicate that the corresponding organisms were active in the formation of these sediments. Considerable caution is necessary in the selection and preparation of ancient sediments for analysis for traces of organic compounds. For example, during the preparation of insoluble residues, fungal hyphae, associated with lichens growing on the rock surface, have been observed to penetrate several inches into the rock. Freshly quarried material and diamond drill cores can be penetrated and contaminated rapidly. Direct bacterial influences
Diverse bacterial activity can hardly be overestimated in (I) the precipitation and solution of carbonates, (2) the transformation and decomposition of both inorganic and organic materials, (3) the control of the pH and Eh of the water medium, ( 4 ) the production of gases and disfiguration of sediments, and (5) the liberation and concentration of minor and trace elements. VINOGRADOV (1 953), ZOBELL(1957), OPPENHEIMER (1960), CLOUD (1962) and KUZNETSOV (1962) in numerous publications have given a list of bacterial processes and discussed their effects on the chemical composition of sediments. VINOGRADOV (1953) gave the following list of elements that are utilized or transformed by Bacteria: C, H, 0, N, P, As, S , Se, Fe, Mn, Al, Ca, Si, and Mg. Probably, future research will result in the addition of other elements to this list. The interesting phenomenon of Mg- and Ca-concentration mentioned by CARROLL(1963) has been presented earlier. This observation is of particular significance as it has been suggested that Bacteria may form a nucleus for calcium carbonate precipitation. TAFTand HARBAUGH (1 964) have suggested that the dark matter in the interior of some dolomite crystals in Recent carbonate deposits may be organic in composition. If one accepts the evidence given by LALOU(1957) and NEHERand ROHRER(1958), which indicates that Bacteria may be able to form dolomite, or at least carkact as nuclei for the inorganic precipitation of carbonates, then one may well suppose that the dark components described by Taft and Harbaugh could be of bacterial origin. The problems encountered by BROECKER (1963, p.2829) in evaluating the
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
75
uranium series inequilibrium as a possible tool for absolute age determinations of marine carbonates, indicate that further studies of diagenetic processes, that may have been initiated and controlled by Bacteria, are of real practical importance. Application of skeletal mineralogy and chemical composition to geological problems
A number of attempts have been made to evaluate the possible use of the mineralogy and elemental composition of calcareous skeletons and organogenic limestones. Some of these possible uses are implied in the paragraphs which follow, in which brief consideration is given to skeletal growth and element uptake and retention, under differing ecological and diagenetic conditions. Mode and rate of shell growth and element uptake Experiments performed on the growth of calcareous shells have furnished some data on the mechanisms and rate of skeleton genesis, and on the role of chemical elements and certain isotopes. Some of the publications, such as the one by LIKINS et al. (1963), have been mentioned elsewhere in this chapter. Additional references are to be found in the chapter on techniques of analyzing carbonates by WOLF et al. (1967) in this book. T. F. GOREAU and N. I. GOREAU (1960) have used radioactive tracers to study skeleton formation in corals. Taxonomic significance In general, little information is available on significant mineralogical and chemical criteria in the classification of plants and animals as a whole. One exception is the attempt by BLACKMON and TODD(1959), mentioned earlier, who have suggested that the mineralogic composition of foraminiferan skeletons should be taken into account when lineages are under consideration. LOWENSTAM (1961) suggested that the discrimination of brachiopods against Sr and Mg, and the mean values of Sr/Ca and Mg/Ca ratios, may be characteristic for the species of various genera and orders of the articulate brachiopods. VINOGRADOV (1953) mentioned that skeletal chemical compositions in Algae, to name only one group, are characteristic for given species and genera and that composition is also related to the organism’s habitat. Mode and degree of diagenetic alterations The tempo of study of diagenetic modifications is increasing with development of more sophisticated techniques supporting the petrographic microscope, and making it possible to measure minute changes. The difficulties involved are, of course, enormous. Investigations on Recent skeletons, ooliths, pellets, various types of lime-muds, and so on, coupled with laboratory syntheses may eventually lead to the establishment of upper and lower limits of element concentration for skeletal and non-skeletal materials for particular conditions. Any increase or
76
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
decrease from the “standard values” would indicate a change, and this in turn may assist in understanding diagenetic-epigenetic alterations. Temperature and salinity interpretations Many factors can influence the mineralogy and chemical composition of calcareous skeletons; however, most attention has been given t o the study of mineralogytemperature, magnesium-temperature, strontium-temperature, oxygen isotopetemperature, mineralogy-salinity, and strontium-salinity relationships, with lesser consideration of other interdependencies of elements within their environment of formation. These are briefly considered here: Mineralogy-temperature relationship. LOWENSTAM (1954a, b) has presented data that leave little doubt that temperature is one of the factors influencing skeletal mineralogy. Closer examination of small taxonomic groups, at the generic or specific level, however, revealed numerous exceptions. Lowenstam found, for example, that limited sensitivity to temperature of shell mineralogy and even a lack of mineralogy-temperature interdependence for some species appears to be linked to semi-terrestrial adaption. In some extreme cases, shell deposition was shown to occur only at elevated temperatures. In another case, Lowenstam reported on two species, occupying essentially the same environmental niche: one was found to be temperature dependent whereas the other was not. The mode of life may intervene as, for example, in the case of pelecypods where only the vagrant benthos show temperature-dependence, whereas sessile or cemented types do not seem to show it. Lowenstam also suggested that salinity may influence the aragonite and/or calcite precipitation of skeletons in addition to temperature and other possible controls. DODD(1961) stated that the mineralogy of the mussel, Mytilus caftforniunus, is not affected by temperature in small specimens, but larger ones show positive temperature-aragonite correlation. In the case of Mytifus edulis the mineralogy is also affected by salinity and shows a negative salinity-aragonite correlation. Dodd concluded, therefore, that Mytifus in the region investigated by him can be useful for paleotemperature and paleosalinity interpretations. Subsequent work by DODD(1962) showed that the shell of Mytifus calijornianus comprises four layers composed of either organic substance, calcite or aragonite. The growth-pattern and structure of some of the layers are believed to represent summer deposition and can be used, therefore, for age determinations of the shell. In turn, the growth rates, which are in part a function of temperature, can be determined; this provides additional paleotemperature data. In a more recent publication, DODD(1963a, b) suggested that a strong phylogenetic effect existed; different species of the same genus showed different temperature-mineralogy relationships which definitely indicate additional influences to those given above. Correlation exists between shell thickness and mineralogy in Mytifus cufifor-
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
77
nianus, whereas mineralogy and shell length correlate in Mytilus edulis diegensis. Shell thickness itself, however, may not affect mineralogy; instead, some unknown factor may control both mineralogy and thickness of calcareous skeletons. Some species have an early stage in their growth that is temperature insensitive, whereas this is not found in other species. In some instances, Mytilus californianus smaller than 20 mm in length showed no relationship between mineralogy and temperature. Both subspecies of Mytilus edulis show negative correlation between salinity and aragonite content. This relationship is not determinable in the case of Mytilus calijornianus, as it is stenohaline in nature. In this connection it should be noted that, with one exception as reported by DODD(1 963b), all fresh-water molluscs are aragonitic. DODD(1963a) concluded that the variations in species and subspecies of Mytilus are not completely explained by any of the factors considered; as yet undetermined influences may be operative in controlling the aragonite content. It seems, however, that Mytilus californianus can be used for paleotemperature reconstructions, if large, complete, unworn, qnd well-preserved shells are used. Shell mineralogy of the two subspecies Mytilus edulis eduli and Mytilus edulis diegensis is possibly useful for paleosalinity determinations. Magnesium-temperature relationship. The magnesium content and the Mg/Ca ratio of calcareous shells certainly reflect environmental temperature as shown by CHAVE (1954a) and CHILINGAR (1953, 1962a). Deviations from the “ideal” temperature-magnesium relationship have been mentioned earlier in the section on magnesium in skeletons. Some other examples that show the degree of reliability of using Mg contents of skeletons for paleotemperature reconstructions are presented here. CHILINCAR (1962a) plotted the Ca/Mg ratios of various organic groups and confirmed CHAVE’S(l954a) observation that there is an inverse (hyperbolic) relationship between the Ca/Mg ratio and the environmental temperature. Chilingar found that in some cases temperature differences as small as 0.5”C are reflected in the Ca/Mg ratios of organisms. Artificially precipitated carbonates also showed an inverse relationship between the Ca/Mg ratios and the temperature. Chilingar, therefore, concluded that “the similarity in shape of ‘Ca/Mg ratio versus temperature’ curves of invertebrates and direct chemical precipitates suggests that the Ca/Mg ratios of these organisms are controlled to some extent by the effect of temperature on solubility products of CaC03, MgC03, Mg (OH)2, etc. The differences in magnitude of Ca/Mg ratio in different organisms may be related to the growth mechanism, and composition and pH of the body fluids.” DODD(1963a) mentioned that the Mg content of the outer calcitic layer of Mytilus increases with increasing environmental temperature, but not so regularly as does the Sr concentration. CHAVE(1954a) observed that the temperature-magnesium trend of a single echinoid species roughly parallels the trend of the entire class. PILKEY and HOWER
78
K. H.
WOLF,
G. V. CHILINGAR AND F. W. BEALES
Species trend
\
Class trend+
/’
L
4 -
Temperature
-
Fig.4. Diagrammatic illustration of temperature-magnesium trends of individual echinoid species and HOWER, as compared to temperature-magnesium trend of the whole class. (After PILKEY 1960; by permission of Journal of Geology.)
(1960), on the other hand, found that the trend of temperature versus MgCO3 content curve of a single echinoid species differs from the trend of the entire class: “the MgC03 content of a single echinoid species changes at a significantly lesser rate than the temperature-Mg trend of the entire class . . . ” They commented that future studies may reveal a step-like succession of temperature-Mg trends as shown in Fig.4. Based on their work, Pilkey and Hower pointed out that although LOWENSTAM (1954a, b) showed a positive correlation with water temperature for the articulate brachiopods at the class level, this relationship may not hold for the specific level of the brachiopods. In conclusion, there appears to be little doubt that in general CHAVE’S (1954a) and CHILINGAR’S (1953, 1962a) temperaturemagnesium correlation is valid but that in many particular instances the relationship has proved to be more complex. Both purely organic-metabolic and purely physicochemical influences appear to be operative, and more research is required on the species and subspecies level before paleotemperature reconstructions can be accepted as reliable. Strontium-temperature relationship. If one considers the observations made by LOWENSTAM (1 954a, b) that the aragonite/calcite ratio in many organisms increases with temperature, and that the Sr content is usually greater in aragonite, then one should expect a relationship between Sr content and temperature. In fact, Lowenstam did notice an increase in Sr content with increasing temperature in the Serpulidae. KULPet al. (1952) and ODUM(1950a, b) had previously reported, however, that no correlation, or at least a very poor one, exists between the Sr/Ca ratio and temperature even for those species the crystal form of which does not vary with temperature. Genera and species that have a wide range of temperature tolerance have similar Sr/Ca ratios in both warm and cold environments. For example, calcareous red Algae and aragonitic gastropods do not show a consistent
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
79
variation pattern of Sr/Ca ratio with temperature in Odum’s table. KULP et al. (1952) and CHAVE (1954a, b) made similar observations; and the latter stated that the incorporation of Sr is quite different from the inclusion of Mg in echinoderms, for example. TUREKIAN (1957) analyzed Atlantic equatorial eupelagic cores for Ca and Sr and found that “when the Globigerina contribution to the Sr and Ca contents of the core are subtracted, a variation in the Sr-to-Ca ratio for the fine fraction is observed which is related to the Ericson temperature curve for the core-the high Sr/Ca ratio corresponding to a time of high surface ocean temperature.” This is best explained by a sympathetic variation in abundance of celestite tests secreted by acantharian Radiolaria. “If the carbonate and lutite sedimentation rates are sensibly constant, then Acantharia productivity is temperature dependent.” Subsequent investigations, however, seem to have shown that the celestite has been depositing at a constant rate and that the variations observed are due to varying rates of calcium carbonate deposition. PILKEY and HOWER (1960) found that Sr/Ca ratio is temperature dependent at the specific level but not at the class level. In a subsequent publication (PILKEY and HOWER,1961) they stated that Sr content of some aragonitic mollusc species exhibits a positive correlation with annual mean temperature; the Sr content of some calcitic molluscs shows a poor negative correlation with temperature but an excellent negative relationship with salinity. One species correlated poorly with all environmental factors examined. DODD(1963a) determined the Sr content of the calcitic prismatic layer of Mytilus and found that it is directly proportional to growth temperature, whereas the Sr content of the aragonite nacreous layer varies inversely with temperature. Combined study of Sr, Mg, and 0 isotope contents of skeletons. Many of the apparently contradictory results obtained in the study of carbonate chemistry and environmental reconstructions are due to the restriction of analytical investigations to only one or two components; and this, consequently, does not permit the detection of possible secondary modifications. LOWENSTAM (1961, 1963) reported investigations of the Sr and Mg contents and the 1 8 0 / l 6 0 ratios of Recent and fossil brachiopods. He demonstrated that SrC03 and MgC03 contents and 1 8 0 / 1 6 0 ratios of Recent brachiopods from waters having salinities close to the average of the oceans (33.5-36.5 %,) are all temperature-dependent. The data presented, however, suggest that the Sr and Mg contents in brachiopods vary not only with environmental temperatures but also with the species and other factors. The use of SrC03 and MgC03 contents in conjunction with l 8 0 / l 6 0 ratios for determining the presence and degree of diagenetic alterations are discussed in the appropriate section below. Other elements-environment relationships. PILKEY and GOODELL ( 1963) stated that
80
K. H.
WOLF, G.
V. CHILINGAR AND F. W. BEALES
aside from studies on Mg and Sr, only a few attempts have been made to evaluate the environment-element relationships for other major and trace constituents. They analyzed seven species of molluscs for Mg, Mn, Ba, Sr, and Fe contents and shell mineralogy, and studied their relationship to both temperature and salinity. The results indicated that no compositional variable is related to environmental temperature in four species. The Mg/Sr, Mn+Mg+Ba+Fe/Sr, and Mn+Mg+ Ba/Sr ratios, and the percentage of calcite correlate with temperature in three species, whereas other ratios or percentages exhibit a relationship in very few (two or less) instances. With two exceptions (i.e., Sr and calcite contents), the nature of the relationships between temperature and any single compositional variable are consistent and the correlations are always inverse or always direct. In general, however, the correlations with temperature are weak, and the differences in salinity cause greater changes in the composition of skeletons than differences in temperature. Thus, PILKEYand GOODELL(1963) concluded that the environment-composition relationships are too weakly defined to be of use in ecological reconstructions in the cases investigated by them. Relationship bet ween salinity cind skeleton composition. TUREKIAN (1955) pointed out that the importance of salinity as a possible independent variable controlling the Sr/Ca ratio in shells and sediments has not been stressed. KULPet al. (1952) also stated that the primary factor controlling the composition is the Sr/Ca ratio in the water medium, which in turn is related to salinity. The effect of temperature, according to them, is only of very minor importance. SAID(1951) reported on a species that was found to have a different skeleton composition in two widely separated localities, both in respect to elements present and the quantities thereof. Amphistegina radiata from the Red Sea has higher contents of practically all the rare chemical elements present than those of the Pacific Ocean specimens. The Red Sea specimens also have tin, whereas those of the Pacific lack it. According to Said, these differences may be due to a higher salinity of the Red Sea, among other possible reasons. More recent investigations have shown that salinity certainly has a marked effect on both shell mineralogy and elemental composition, but the relationships once again are far from being simple (PILKEYand HOWER,1960), as illustrated here by a few examples. PILKEY and GOODELL (1962) found that of several mollusc species some showed a positive correlation of Sr content with temperature, whereas others exhibited poor negative correlation with salinity. Except for one species, an inverse relationship between salinity and Sr content is present to some degree in all the molluscs studied. In a subsequent study, PILKEY and GOODELL (1963) demonstrated that the differences in salinity result in a greater modification of mollusc shell composition than do temperature variations, but that salinity concentration above 25z0 do not markedly affect the composition of the skeletons. Pilkey and Goodell showed,
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
81
however, that salinity-composition interdependence is too weak to permit reliable paleoecological reconstructions. RUCKER and VALENTINE (1961) measured the concentrations of Mg, Sr, Mn, Na, Cu, and B in 71 shells of Recent Crassostrea virginica. They found that Mg+Sr and Mn contents are statistically inversely related to salinity. The Na content correlates directly with salinity; however, it is interpreted as not being part of the carbonate shell, and is thought instead to be present in interstitial salts deposited from sea water trapped in the skeleton. Contents of the other elements show no significant relation to either salinity or temperature. Rucker and Valentine concluded that the “multiple-regression technique based on the concentrations of Mn, Na and Mg+Sr permits the prediction of the environmental salinity of shell growth for Crassostrea virginica within a rather large standard error (5.3 %)”. DODD(1963a) reported a marked increase of Mg content in the outer calcitic prismatic layer of Mytilus with decreasing salinity. The Mg concentration in the aragonitic nacreous layer was too low for accurate measurements. Regarding the relationship of Ba and Sr to salinity, LANDERGREN and MANHEIM (1963) presented arguments showing that Ba is not a useful salinity indicator 8s based on our present knowledge, except possibly in rare cases. According to LEUTWEIN (1963), the Ba/Ca ratio increases in fresh water, whereas the Sr/Ca ratio decreases. Many exceptions to this rule, however, have been recorded. The excellent work by LOWENSTAM (1961, 1963), already mentioned in the section on temperature-element correlation, indicated that Sr and Mg contents of articulate brachiopods are partly related to temperature; however, other influences seem to be operative. Lowenstam, therefore, examined specimens from hypersaline and hyposaline environments and compared them with those of normal marine localities with similar water-corrected 1 8 0 / 1 6 0 ratios. It was found that the SrC03 contents and the Sr/Ca ratios of the skeletons are sensitive to changes in Sr concentration and Sr/Ca ratio of the water medium, and that the magnitude of changes differ for hyper- and hyposaline waters. Lowenstam also reported that in spite of proportional differences in Mg and Ca contents in hypo- and hypersaline waters, the uptake of Mg into brachiopod skeletons varies. He suggested that the absolute Mg concentration in the water medium is the important factor in determining the Mg content of the shells, but other influences are operative and complicate the relationship. ODUM(1957b) concluded that “ . . . it is possible to use analyses of Sr/Ca ratios to determine whether fossil skeletons that are unreplaced are marine or fresh-water . . If the Sr/Ca ratio is higher than the Sr/Ca of ocean species a nonmarine locality with a high Sr/Ca ratio can be recognized, but if the Sr/Ca ratios are close independent evidence is required for proper interpretation . . .” Inasmuch as closed lakes may resemble the oceans in having high Sr content, the Sr/Ca ratio cannot always indicate the difference between inland closed basins of sedimentary drainage and the ocean. In a table, ODUM(1957b, table 32) showed the
.
82
K. H. WOLF, G . V. CHILINGAR AND F. W. BEALES
use of Sr/Ca ratio in fossil skeletons for determining the nature of ancient environments. He recognized two groups: ( I ) fossils with high Sr/Ca ratio, which possibly indicate marine and arid lake origin, ground-water source, or volcanic drainage; and (2) fossils with a low Sr/Ca ratio which are indicative of origin in fresh water having a low Sr/Ca ratio. These two groups are so all-inclusive, however, that they are of little applicability in precise geochemical interpretations. Odum admitted that in controversial cases independent criteria have to be used, e.g., type of fossil assemblage. KUBLER (1962) investigated the Sr content of two sedimentary cycles composed of marine to lacustrine deposits and found a range of about 1,OOO to 5,000 p.p.m. He did not find a distinctive difference that could be attributed to the salinity factor. The foregoing considerations compel one to agree with ODUM(195713) that the Sr/Ca ratio is not a complete answer in salinity reconstructions; however, in many cases it can be helpful if used with other sources of evidence. The present state of our knowledge permits us to support other data useful in recognizing specific environments with information on the Sr/Ca ratios. These data may assist in attempts to interpret ancient environments but too little is known about Sr-Ca partition during genesis, or modification during diagenesis, to permit definitive interpretations based on Sr/Ca ratios alone. Skeleton-environment relationships, and “Law of Minimum in Ecology and Geochemistry”. Some insight has been gained into the factors that control directly and indirectly, separately and in combination, the mineralogic and elemental composition of the calcareous skeletons of both plants and animals: carbonate polymorphism, temperature, salinity, phylogenetic level, growth rate of shells, multimineralogic composition, seasonal and life-span variations in composition and mode of development, biochemistry of body fluids, adsorbed and absorbed impurities, solubility products and other conditions in the depositional medium, non-uniform degree of effects with changing physic0 chemical conditions (e.g., salinity effects are absent in some cases above 25%,, but are distinct below that value), mode of life (e.g., planktonic versus benthonic; crawlers versus borers and burrowers), mode of food-intake, and many others. The published results so far indicate that if the composition of skeletons is to be used for definite paleoecological reconstructions, it can be done with confidence only at the specific level. One promising approach is suggested by the work of PILKEY and GOODELL (1962) who found that certain species of molluscs are either temperature- or salinity-insensitive to varying degrees. By the simultaneous use of shells of more than one of these species, it may be possible to make both paleotemperature and paleosalinity interpretations. Wherever possible, shells composed of either calcite or aragonite should be utilized to eliminate complex
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
83
effects due to polymorphism. More than one variable should be determined in large samples to enhance the reliability of the interpretations made. With an increase in the data on environment-organism and environmentmineral relationships, the familiar Law of Minimum in Ecology may be expanded to include minor and trace elements, and inorganically and organically formed minerals, and be designated instead The Law of Minimum in Ecology and Geochemistry (WOLF,1963b). Briefly stated, the geochemical phenomena that are sensitive to environmental conditions can be used in conjunction with biological data as criteria to narrow down environmental ranges. WOLF(1965a) demonstrated the partial application of this principle to a Devonian reef study. Environmental reconstructions of regional trends in skeletal mineralogy and chemical composition Regional trends in both the mineralogy and chemical composition of skeletal carbonate sediments have been shown by CHAVE (1962) to depend not only on the particular organisms present in the different environments, but also on the size of the organisms, selective physical destruction, transportation, and differential solution. In addition to these, the work of MAXWELLet al. (1964) suggested that selective removal of various components by winnowing and differential transportation-accumulation is significant. CHAVE(1962) illustrated that in the recent reef complex in North America studied by him, the highest ratio of high-Mg to low-Mg calcite is in the reef vicinity due to coralline Algae Lithothamnion and Lithophyllum, and encrusting Foraminifera Homotrema. The lowest value of this ratio is found in sediments from deeper waters because of the abundance of planktonic Foraminifera, e.g., Globigerina. The highest percentage of aragonite is present in shallow waters due to the abundance of the aragonitic corals and molluscs and aragonitic alga Halimeda in lagoons. This seems to agree with the observations made previously by CHAVE (1954a, b) and STEHLIand HOWER (1961) that only in quiet deep water is calcite the predominant mineral phase. In other parts, aragonite and high-Mg calcite form the main components of recent sediments. Inorganic processes may also control the mineralogy as suggested by CHAVE’S observations (1962) that: ( I ) near-reef sediments contain less aragonite than the nearby lagoonal sediments; and (2) the mineralogy changes with grain size. He concluded that inasmuch as the living reef is mainly composed of aragonitic madreporarian corals and molluscs, and that the calcitic alcyonarian corals, coralline Algae and Foraminifera are of minor quantitative importance (sometimes, however, they are responsible for the local high-Mg calcite concentration), it seems probable that a non-biologic process or processes remove aragonitic debris. Chave suggested that perhaps differences in durability of aragonitic versus calcitic material may be the causal factor. Change of mineralogy with grain size
84
K. H. WOLA,,G . V . CHILINGAR AND F. W. BEALES
is reflected in a regular increase in mineral stability, with associated decrease in mineral solubility, from coarse to the fine fractions of the carbonate sediments (CHAVE,1962). According to him, there is a decrease in aragonite percentage and a decrease in the ratio of high-Mg to low-Mg calcite from the coarse to the fine sizes. This regular change has been found in a wide range of environments. For this reason, and because of the fact that the sediments of deep-water environments are largely composed of calcite, it appears that in the case of CHAVE'S(1962) studylocality, differential removal by washing and transportation to a more favorable site of accumulation is not applicable. Under other conditions such as those described by MAXWELL et al. (1964),however, a differential washing process may be of major importance. To understand his observations, Chave considered, among other explanations, inversion from aragonite to calcite and removal by solution as possible processes. Inversion was dismissed as an unlikely mechanism based on his belief that it would not be controlled by grain size in contrast to solution. Chave concluded, therefore, that solution is the most plausible cause of the regular increase in mineral stability with decrease in size. It should be noted, however, that in general the relationship between grain size and degree of inversion needs verification for reasons pointed out elsewhere in this chapter. A number of other independent investigations of Recent carbonate sediments indicated that selective removal by solution seems to be a rare phenomenon in the warm, shallow-marine environment. Age determination BARNES et al. (1956) suggested that it may be possible to date corals by the U-10 (uranium-ionium) method as far back as 300,000 years, because the 238U decay series in recently formed marine coral is systematically out of radioactive equilibrium. Subsequent investigations by TATSUMOTO and GOLDBERG (1 959) revealed the presence of substantial amounts of uranium in oolites, and studies thereof led to the conclusion that dating of oolites based on growth of ionium (thorium-230) from uranium also seems possible. BROECKER (1 963) furnished data, however, which demonstrate that fossil molluscs have a higher uranium content than living forms. Various lines of reasoning led Broecker to dismiss both the species effect and the change in U/Ca ratio of sea water during geologic time. He concluded that the excess uranium is secondary and of very early origin. One possible explanation for the excess of uranium being added shortly after death, while the organism was still in contact with the marine environment, is perhaps bacterial destruction of the organic matrix which sets up a microenvironment favorable for U precipitation. I t is important to note here that the origin of the uranium in organisms must be precisely known before the reliability of these materials for dating can be evaluated. (1963) also found that zz6Ra in any fossil carbonate can be divided BROECKER into five types according to origin and that only two are useful for age estimates. Thus, use of the Z26Ra/238Uratio in determining the absolute age of marine carbon-
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
85
ates results in highly misleading ages. Broecker concluded that “criteria based on internal agreement of the isotopic data (i.e., 234U, 230Th, 226Ra, and where possible, 231Pa), other diagnostic parameters (microscopic examination, aragonite content, 13C/12C, 180/160, 232Th content, 238U content, 234U/238U, etc.) and material type (for example, coral and oolite are obviously more suitable than the average mollusk) will have to be developed”. Correlation based on composition K u D Y M o v ( ~in~ his ~ ~ book ) Spectral Well Logging has shown that correlation based on the minor and trace-element contents of carbonates and non-carbonate sediments can be most useful. CHILINGAR and BISSELL (1957) used Ca/Mg ratio for correlation purposes in studying the Mississippian Joana Limestone of the Cordilleran miogeosyncline. (Some discussion on this subject is presented in the section on “Regional aspects of carbonate composition” in this chapter. Basis for exploration philosophies GARLICK(1964) and MALAN(1964) described the pattern of metallic mineral distribution in reef complexes. Malan showed that copper is mainly concentrated in the inter-reef argillites. Various other attempts have been made, mainly by commercial companies, to use trace elements or other geochemical gradients to assist in the search for oil and gas deposits or metallic ore bodies. They have not been conspicuously successful to date; or if they have, the results have been kept as well-guarded secrets. Despite the difficulties that are bound to be encountered, the search for such indicators should be continued unless and until it has been proven futile. The objective is to develop criteria that are sufficiently diagnostic to reduce the number of test bore holes necessary for reconstruction of paleoenvironments and yet to permit conventional stratigraphic correlation. The present state of the research seems to be one of adding interesting corroboration of results already understood rather than one of developing an exploration tool. The authors were informed (confidential data), however, that the use of Ca/Mg ratios (plotting lines of equal Ca/Mg ratio and recording directions in which these ratios decrease) in locating dolomitized (and porous) carbonate oil reservoirs proved to be of value in some areas. INORGANIC FACTORS AND PROCESSES RELATED TO ELEMENTAL COMPOSITION OF CARBONATES
The problems related to the mineralogic and elemental composition of inorganically formed carbonates can conveniently be discussed under the following headings: ( 1 )inorganic physicochemical precipitation of calcium carbonates; (2) mechanical, volcanic, and cosmogenous contaminations; (3)magnesium in inorganic carbonates;
86
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
( 4 ) strontium in inorganic carbonates; (5) other elements in inorganic carbonates, and associated contaminants; (6) elemental composition of environment controlling precipitation and stability of vaterite, aragonite, calcite, and dolomite; (7) environmental influence on the particle form of carbonate precipitates; and (8) influence of chemical composition of depositional medium on organisms.
Inorganic physicochemical precipitation o j calcium carbonates
The numerous parameters and processes that cause inorganic enrichment, depletion, and migration of chemical components cannot be considered in this chapter. Due attention has been given to them in other chapters of this book, and additional information is available in the publications by RANKAMA and SAHAMA (l95O), KRAUSKOPF (1955), GARRELS (1960), GOTO(1961), and others. Most interesting from the petrologic point of view is the recent observation made by ANGINOet al. (1964) indicating that inorganic processes, which are usually associated with warm and temperate climatic zones, can be expected to be operative also in unusual localities. Angino and co-workers observed the precipitation of gypsum (CaS04), aragonite (CaC03) and mirabilite (NazS04) in the permanently ice-covered Antarctic Lake Bonney where water temperature ranges from -3.5 O to 7 “C. These investigators stated that “an analysis of ionic ratios suggests that the lake waters may consist of trapped sea water highly modified by subsequent concentration by evaporitic processes, by addition of ions from surrounding soils, and by addition of warm spring water”. Mechanical, volcanic and cosmogenous contaminations
Any type of discrete detrital particle that can occur in sedimentary rocks can, in general, also be expected to be present in carbonates. Many of these mechanically added components constitute the “insolubles”, such as clay and different types of silt and sand grains. Under certain conditions, however, carbonate sediments can be diluted by calcareous and dolomite detritus derived from an older source. In precise geochemical studies these contaminations must be carefully considered, for the older carbonate-rock fragments may have been in equilibrium with a different physicochemical environment. Volcanic emanations, both on the continent and in the ocean, can contribute solid particles, as well as gases and fluids to an environment of carbonate sedimentation. Some of the geochemical problems involved were discussed by STRAKHOV (1964) who stated that little is known about the contribution of volcanic material to sediments in general, or about the chemical contamination arising therefrom. Cosmogenous contamination of shallow-water carbonates may be negligible because of the high rate of sedimentation and the possible immediate removal by
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
87
reworking processes. In localities where the rate of accumulation is extremely slow, however, a cosmogenous source for some of the chemical constituents should be considered. WISEMAN (1964), for example, mentioned that the components of Mid-Atlantic deep-sea sediments are derived from lithogenous, biogenous, hydrogenous (= derived from the surrounding body of water) and cosmogenous sources. In this case, however, after taking into account numerous variables, Wiseman tentatively concluded that the presence of trace elements can be explained without assuming an appreciable addition from a cosmogenous source. Magnesium in inorganic carbonates
It has been mentioned earlier that the maximum MgC03 content of inorganically precipitated calcium carbonate is approximately 4 % in contrast to the maximum value of about 30% in organically formed carbonates. The statement of CHAVE (1954a, b) that there is no evidence of inorganic processes forming high-Mg calcite under surficial conditions appears to be in general true, but one has to count on minor exceptions and, in particular, on early diagenetic alteration of precipitated carbonates. In the study of naturally formed sediments, it is very difficult to determine whether the Mg in carbonates was coprecipitated (as MgC03, Mg ( O H ) 2 , x Mg CO3. y Mg ( O H ) 2 . z HzO, etc.) or whether it has been added diagenetically by adsorption-diffusion-absorption processes, for example. In doubtful cases, therefore, it is not possible to discuss the limits of Mg uptake meaningfully (or that of any other element) without first precisely knowing the mechanisms involved. The Mg in carbonates can occur as: ( I ) magnesite or hydromagnesite (e.g., ALDERMAN and VON DER BORCH,1961); (2) dolomite (e.g., ALDERMAN and VON DER BORCH,1961, 1963; PETERSON et al., 1963; SKINNER 1963; TAFTand HARBAUGH, 1964); (3) ankerite (e.g., USDOWSKI, 1963a; BROVKOV,1964); ( 4 ) high-Mg calcite (e.g., KUBLER, 1962, mentioned calcite with 40 % MgC03; FUCHTBAUER and GOLDSCHMIDT, 1964, reported on a calcite with 18% MgC03; occurrences were also noted by STEHLIand HOWER,1961; SEIBOLD,1962; TAFTand HARBAUGH, 1964); and (5) low-Mg calcite (e.g., SEIBOLD, 1962; USDOWSKI, 1962; TAFT and HARBAUGH, 1964). SKINNER (1963) showed that the Mg of a sedimentary deposit can be present in more than one phase; the predominantly inorganic carbonates of South Australia investigated by her are composed of magnesian calcite, calcian dolomite and dolomite, and magnesite and hydromagnesite. Strontium in inorganic carbonates
The problems of Sr concentration in inorganically formed carbonates must be considered from two view-points: ( I ) contemporaneous coprecipitation of Sr, and (2) subsequent introduction of Sr into the carbonate. ODUM(1957b) stated that in most cases it appears that the Sr/Ca ratio of a carbonate is smaller than that of the
88
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
solution from which the carbonate was precipitated. In some occurrences, however, some very high Sr/Ca ratios were observed indicating that certain sedimentary processes can lead to Sr/Ca values equal to or greater than those of the aquatic medium. In one case the ratios were comparable: the Sr/Ca ratio of the oolite sediments, Great Salt Lake, Utah, is 4.23/1,000 atoms and is nearly equal to that of the water (4.20/1,000 atoms). Odum mentioned that if the solubility products are much exceeded, and if the solutions have no possibility to exchange with a large reservoir, precipitation occurs in a closed system and the Sr/Ca ratios of the precipitates are equal to those of the solution. For example, in five experiments the addition of sodium carbonate to sea water (Sr/Ca = 9.0/1,000 atoms) at various rates, produced in all cases calcium carbonate precipitates with Sr/Ca ratios ranging from 4.9 to 13.3/1,000 atoms. Similar results were described by ZELLERand WRAY (1 956). They also found that the Sr/Ca ratio increases with successive precipitation. WATTENBERG and TIMMERMANN (1938, in: SVERDRUP et al., 1952, p.211) reported that the solubility product of carbonate in sea water is approximately the same for both Sr and Ca (5 * lo-’), in contrast to distilled water where it is much smaller for strontium carbonate (0.3 * than for calcium carbonate (5 10-9). This suggests that the Sr/Ca ratios of directly precipitated carbonate should be higher in lowsalinity water. On investigating the coprecipitation of Sr with calcium carbonate from aqueous sdutions, OXBURGH et al. (1959) found, in agreement with many other investigators, that Sr2+ ions are much more readily precipitated with aragonite than with calcite. They also mentioned that it is possible to estimate the Sr2+/Ca2+ ratio of the solution from which the precipitation took place. GOLDBERG (1957) stated that examination of inorganically precipitated calcium carbonate from sea water in the laboratory, and studies of artificially prepared oolites, show that aragonitic structures contain more Sr relative to Ca than does the sea water. On the other hand, the Sr/Ca ratio in sea water is higher than that of most aragonite-precipitating organisms. HOLLAND et al. (1963) discussed the chemical composition of ocean water and its bearing on the coprecipitation of Sr with oolites. They stated that according to the mean value of the concentration of Sr as compared to Ca, one should expect a content of about 9,060 p.p.m. of Sr in aragonite precipitated from sea water at 25°C. Holland and co-workers mentioned that this is within the range of values found for the Sr concentrations in oolites from Cat Cay, Bahamas. ODUM(1957b) made it clear that it is difficult to evaluate the applicability of the principle that rapid or restricted inorganic precipitation gives rise to high Sr/Ca ratios, because the exact physico chemical mechanisms are still in dispute. For example, aragonite-needle deposits are believed by some to be derived from calcareous Algae, whereas others have suggested a bacterial or physico chemical origin. Future investigations of the Sr/Ca ratios may cast some light on these problems. As Odum indicated, the situation is made somewhat difficult by the
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
89
presence of reef corals and aragonitic green Algae having Sr/Ca ratios of 9-12/ 1,000 atoms and 10-13/1,000 atoms or greater, respectively. The Sr/Ca values are high (9/1,000 atoms or greater) in three occurrences (in the Bahamas, Key West, and fossiliferous carbonates of Miami), where direct precipitation is assumed by some investigators: ( I ) unconsolidated and consolidated oolite (9/1,000 atoms); (2) drewite (9.3/1,000 atoms); and (3) consolidated and cemented rocks composed of fragments of taxonomic components originally not high in Sr content. The high Sr/Ca ratio of the drewite is comparable to the high value of calcareous green Algae; however, it is also similar to the Sr/Ca ratios of some types of inorganic precipitates from sea water. The Sr/Ca ratio does not, therefore, allow a precise evaluation of depositional environment. The mechanism that results in the cementation of beach-rock is still problematic, and the explanations vary from inorganic to organic processes, as reviewed by CHILINGAR et al. (1967). ODUM(1957b) mentioned Cloud’s suggestion that bluegreen Algae in the upper zones cause solution and reprecipitation due to large diurnal pH changes associated with algal metabolism. It is possible thatc)he high Sr/Ca ratios of all reef corals are due to the fact that the skeleton-building colonies contain symbiotic Zooxanthellae and green Algae which produce similar pH changes. Hence, the Sr/Ca ratios of cemented beach sands, calcareous Algae, and reef corals may all be related to the algal processes. It must be concluded, therefore, that studies of minor and trace elements of the beach-rock cement may be helpful in understanding its precipitation. Textural features of Devonian and Recent reef limestones support the concept that Algae can cement beach sands (WOLF, 1963b, 1965~).ODUM(1957b) suggested that if rapid precipitation is required for oolite genesis, the very great vital activity of organisms (photosynthesis) in shallow water and reef environments may be partly responsible. High Sr/Ca ratios (greater than 9/1,000 atoms) may be a paleoecological indication of algal photosynthesis. More research, however, is needed before this line of reasoning is substantiated. In the above discussions it was assumed that the Sr was located in the carbonate lattice. Under favorable conditions, however, celestite may form as an accessory mineral in carbonate sediments. SKINNER (1963) pointed out that in the recently formed sediments composed mainly of calcite and dolomite, the Sr is present as celestite, and the Sr content ranges from 0.28 to 1.12%. The strontianite deposits discussed by HARDER (1964) have been explained by some as being the product of lateral-secretion processes of solutions which derived the Sr from the limestones and organic skeletons. Others have suggested a hydrothermal origin. Harder showed that the limestones and fossils do not indicate any depletion of Sr and that there are no lateral changes in Sr content from the limestones to the strontianite layers; this precludes a lateral-secretion origin. Inasmuch as hydrothermally generated strontianite usually contains Ba, Cu, Pb, Zn, and other elements, and because Harder found that these elements are either absent or are present in traces, he concluded that a hydrothermal origin is
90
K. H. WOLF, G. V. CHILINGAR AND F. W. BEALES
also unlikely. He proposed, therefore, that ascending solutions from the lower Zechsteinsalzen rocks (evaporite-rich deposits) precipitated the strontianite. The fact that the calcite was deposited prior to strontianite indicates that NaCl solutions carried the Sr, because fresh water would have precipitated strontianite first. This supports the viewpoint that the Sr was derived from the lower evaporites. Other elements in inorganic carbonates, and associated contaminants A number of trace elements, other than Sr and Mg, have been reported from inorganically formed carbonate fractions of limestones. Considering the bulk composition of carbonates, it is frequently very difficult to make a distinction between the carbonate portion and the non-carbonate “impurities”. For example, DEGENS et al. (1962) determined the concentration of the following trace elements (in p.p.m.) in petroleum-bearing fresh-water carbonate concretions: B(290-420), Mn(35400), Ni( 3,000). It is not quite clear to what extent some of the elements in the concretions may have been adsorbed-absorbed from the petroleum. OSTROM (1957) stated that “the average content of barium, manganese, and strontium, and the average range of Ba and Mn in the limestone samples, are higher than the averages and ranges of these elements in the shale samples. This suggests that these elements commonly are more closely associated with the minerals composing limestone than those of the shales”. The average amounts and ranges of the other twelve trace elements studied by Ostrom (ByCr, Cu, FeyPb, Mo, Ni, K, Na, Ti, V, Zn) are highest in the shales. The data on Ba given by Ostrom differ from those furnished by LANDERGREN and MANHEIM (1963). As shown in Table XI, there is no enrichment in the case TABLE XI DISTRIBUTTONOF
Ba AND Sr IN
SEDIMENTSOF THE PACIFIC (glton)
and MANHEIM, 1963, table 6) (After LANDERGREN
Ba content (average) Ba content (range) Ba/Ca ratio Ca content (average) Sr content (average) Sr content (range) Sr/Ca ratio
Clay sediments
Calcareous sediments
1,170 300-2,500 0.12 9,600 200 85-580 0.021
1,070 800-1,350 0.0035 306,000 1,480 940-2,000 0.0048
91
ELEMENTAL COMPOSITION OF SEDIMENTARY CARBONATES
of Ba. On the other hand, Sr content is higher in calcareous sediments than in clay deposits by a factor of 7; this, in general, agrees with the observations of Ostrom. In this connection, it is interesting to note that in the algal bioherms studied by MALAN(1964) the copper is concentrated not in the carbonate deposits but in the inter-reef argillites. Malan concluded that this type of occurrence supports a syngenetic origin of the metalliferous deposits, because secondary processes would most likely concentrate the copper within the carbonates. The latter have greater susceptibility to solution, and replacement, than the argillites. This leads one to the controversies of syngenetic versus diagenetic and epigenetic origins of chemical components in carbonate skeletons, minerals, and rocks that are considered in some detail later in this chapter. K. G. BELL(1963) mentioned that the average content of syngenetically formed uranium of carbonates is
3*1
23*2
70' 1
+
0 77 236
99 91 77
0 18 36 49 64 75 86 100
99 95 85 74 58 43 27 trace
0 3
+
99
0
+
trace 9 23 trace 5 15 26 42 58 63 99
+
trace 100
4
* ga
8
g
2;
az cl
>
6
0
z
2;
TABLE111 ARAGONITE IN CONTACT WITH MAGNESIUM SOLUTIONS OF VARIOUS CONCENTRATIONS1
Experiment
Chemistry of solution
Volume (nil!
Weight of precipitate (g)
50
0.2011
Temp. ("C!
Duration OJ experiment (days)
~~
3
2 p.p.m. Mg
4
2 p.p.m. Mg
50
5
5 p.p.m. Mg
50
0.1921
0.2010
23'2
70+1
23*2
0 28 54 70 86
Mineralogy Aragonite (weight %)
99 I0 45 15
+
Calcite (weight %) 1 30 55
0
85 100
0 40 I0 90 110
99 t 65 30 10
1 35 I0 90
0 8 15 33 I0 86 100
99 99 99 99 99 99 99
0
+ . +
130
5 p.p.m. Mg
50
0.2000
IO-tl
0 4 19 29
99 80 30 0
11
5 p.p.m. Mg
40
0.2188
23*2
0 108 246
100 14 trace
100
1
1
1 1 1 I 1 1 20 I0 100
0 26 99 -I
10
10 p.p.m. Mg
40
0.331 1
23*2
0 108 246
100 74 0
0 26 100
55
26 p.p.m. Mg
40
0.1 140
23'2
0 3 13 24 141
91 90 91 90 87
9 10 9 10 13
+ + + +
.
115
49 p.p.m. Mg
40
0.1008
23+2
0 66 180 300 365
99 99 99 99 99 J-
trace trace trace trace trace
131
10 p.p.m. Mg
50
0.2003
23*2
0 121
99
trace
133
10 p.p.m. Mg
50
0.2004
70-t1
0 12 29
trace
55 99
99 99
trace trace
136
50 p.p.m. Mg
50
0.1998
70*1
0 38
I 42
250 p.p.m. Mg
50
0.1997
70*1
0 38
11-G
1,330 p.p.m. Mg
50
0.1Ooo
23'2
0 120 200 320
400 470 1
+ 99 + 45
+ + 99 + 99 + 64 63 64 61
64 64
trace
+
i
$3
trace trace 36 37 36 39 36 36
Mineralogy is presented in weight :L and appears to be dependent upon temperature and quantity of magnesium ions relative to weight of precipitate.
L
5
158
W. H. TAFT
essentially 100% aragonite to calcite (Fig. 1). Of particular interest is the curve at 23 "C (Fig. 1) (close to standard temperature), which suggests that aragonite in contact with distilled water would recrystallize to calcite in less than 6 months in the natural environment. Magnesium effect
Because of the metastable nature of aragonite (JAMIESON, 1953; MACDONALD, 1956), any condition that slows down or prevents solution of aragonite and its reprecipitation as calcite may be a controlling factor that enables solid-state recrystallization to be the dominant process. KITANO and HOOD(1961) described the influence of organic material on the polymorphic form of CaC03 precipitated. In addition, organic matter secreted by carbonate shell-secreting organisms prevents chemical reaction between interstitial water and calcium carbonate of the shell until chemical or biological activity removes this layer. Magnesium ions in contact with aragonite appear to be capable of preventing recrystallization to calcite for an indefinite period by the process of solution and reprecipitation. Temperature and concentration of magnesium ions relative to quantity of aragonite appear to be important factors (Table 11,111).The empirical weight ratio of aragonite to magnesium in solution was termed the critical concentration ratio (TAFTand HARBAUGH, 1964). This ratio (Table 111) is critical to long-term aragonite preservation at laboratory temperature (23*2 "C), but changes with increasing temperature. At 2312 "C, 50 ml of a 5 p.p.m. solution of magnesium in contact with 0.2010 g of aragonite prevents aragonite solution and reprecipitation as calcite (Fig.2). If the temperature is increased to 70 "C, TABLE 111 EFFECT OF MAGNESIUM ION CONCENTRATION ON
Experiment2
3 11 10 5 131 55 115
Critical concentration ratio3 2,011 1,394 827 804 400 109 51
RE CRYSTALLIZATION^ Recrystallized Yes
no
+ +
+
+
+ + +
Based on empirical results from Table 11; temperature 23 f 2°C. Taken from Table 11. Grams of precipitate (in contact with solution)/grams of magnesium in solution.
159
PHYSICAL CHEMISTRY OF FORMATION OF CARBONATES
40
80
100
Tome (days1
Fig.2. Recrystallization of aragonite to calcite as a function of weight ratio of aragonite to magnesium ions available in the solution. This ratio in experiment 3 (Table 11) is 2,011 ;recrystallization is complete within 87 days. The same ratio for experiment 5 (Table 11) is equal to 804; no detectable recrystallization occurs within 100 days.
100
0
0
49.4 p.p.m.Mg2’(115)
0
1
0
26 pp.m.Mg2+(55)
L c
-
u
k
n
40-
20
-
0-
I
I
Fig.3. Lack of recrystallization to calcite of aragonite in contact with solutions having 49.4, 26 and 1,330 p.p.m. of Mgz+. Numbers in parentheses refer to experiment numbersfrom Table 11.
solutions containing 5 and 10 p.p.m. of magnesium are ineffective, but 50 p.p.m. of Mg at this temperature prevents recrystallization (Table 11). Sea water contains 1,330 p.p.m. of Mg2+ which is sufficient to prevent recrystallization (Fig.3). In some instances, the magnesium concentration in interstitial water of fine-grained modern carbonate sediments tends to increase during compaction. Therefore, as interstitial water is squeezed from these sediments, magnesium ions remain
160
W. H. TAFT
in sufficient quantity to prevent recrystallization. If magnesium ions are flushed before lithification, however, recrystallization by solution and reprecipitation appears possible.
Calcium effect Increasing the quantity of magnesium ions relative to the amount of aragonite tends to prevent recrystallization if the critical concentration ratio is 804 or less (Table IV). Calcium ions, on the other hand, react in just the opposite manner. If the concentration of calcium ions relative to quantity of aragonite is increased, the rate of aragonite recrystallization to calcite also increases (Table IV, Fig.4). In addition to calcium ion concentration, temperature, and pH of the solution affects the recrystallization rate (Table IV). At 3 "C, recrystallization is sluggish, but with less calcium at 70°C recrystallization is complete within three days (Table IV). In order to investigate the effect of pH on recrystallization rates, 10 ml of an ethanolamine buffer solution (pH= 10.4) was added to 30 ml of a 400 p.p.m. solution of calcium in contact with 0.2006 g of aragonite at 70°C. Based on previous experiments of aragonite in distilled water (Fig. I), and aragonite in contact with 400 p.p.m. of Ca2+(Fig.4) that recrystallized to calcite within 3 days, this mixture at adjusted pH should have recrystallized similarly. This, however, was not the case (Table IV). During the 20 days duration of this experiment, no recrystallization to calcite was detected. Although this relationship indicates that pH may play a role in affecting recrystallization, it would be unusual to find pH values this high (10.4) in the natural environment.
01.000 p.p.m. Ca2+ A2.500p.p.m. Ca2+ 400pp.m. Ca2+
C P,
L U
20 -
0
0
I
5
Ib
115
2b
; 5
do
i5
do
-
d5
20
Time (days)
Fig.4. Dependence of recrystallization rate of aragonite to calcite upon Ca2+ concentration. Recrystallization rate increases with increasing Ca2+ion concentration.
TABLE IV ARAGONITE IN CONTACT WITH SOLUTIONS CONTAINING VARIOUS CONCENTRATIONS OF CALCIUM IONS AND AT DIFFERENT TEMPERATURES
Experiment
Calcium
Chemistry of solution
400 p.p.m. Ca
Volume
Weight of precipitate
(mil
(gl
Temp. ("C)
0.2008
23*2
50
Mineralogy
(days)
Aragonite (weight %)
Calcite (weight %)
99 90 17 55 30 7 trace 99 80 70 60 25 5 99 80
trace 10 23 45 70 93 99 trace 20 30 40 75 95 trace 20
1 0 99 0
99 100 trace 100
0 22 32
40
Calcium
Calcium Calcium
Calcium
1,OOO p.p.m. Ca
2,500 p.p.m. Ca
400 p.p.m. Ca
1,OOO p.p.m. Ca 2,500 p.p.m. Ca 720 p.p.m. Ca
300 p.p.m. Ca solution adjusted to pH 10.4 with ethanolamine buffer
50
50
50
0.2008
0.1996
40
0.1998 0.2002 0.1940
40
0.2006
23'2
23'2
70*1 3*1
70*1
F
Duration of experiment
15
Calcium
zcl
44 46 0 10 13 15 21 24 0 6 9 12 13 0 1
0 9 81 115 237 0 2 6 14 20
cl
+ +
50
+
99 99 97 97 89 99 99 99 99 99
+ +
+ + + + +
+
50
trace trace 3 3 11 trace trace trace trace trace
zi?! 8
g 5
az
8
c, >
tiz
5
E
162
W. H. TAFT
Effect of other ions Potassium and sodium chlorides increase the recrystallization rate of aragonite to calcite (Table V). The recrystallization rate also increases with increasing concentration of chlorides (Fig.5). Strontium has a retarding effect (Table V), similar to that of magnesium, and prevents recrystallization. The quantity of strontium necessary to preserve aragonite (> 100 p.p.m.), however, exceeds that present in sea water (8 p.p.m.). During precipitation of aragonite, in one instance the writer obtained vaterite with a trace of aragonite and a trace of calcite. In order to test whether or not vaterite could possibly be preserved in marine sediments, vaterite was placed in contact with distilled water and solutions containing magnesium and calcium ions (Table VI). No attempt was made to construct a calibration curve for the three carbonate minerals aragonite, calcite, and vaterite. By comparing the relative intensities of the more intense reflections of these minerals, however, one can obtain a general idea concerning their relative abundance. The second most intense peak of vaterite (intensity= 75; d=3.29) correspondsvery closely to the third most intense peak of aragonite (intensity= 52; d=3.273); and, therefore, as vaterite recrystallizes to aragonite, this peak does not diminish as rapidly as it should. Nevertheless, from the results presented in Table VI, one can conclude that vaterite, if formed in the marine environment, would recrystallize and be preserved as aragonite. If vaterite comes into contact with distilled water, or water containing calcium ions alone, recrystallization to calcite will be rapid.
100
3,000 P.pm CI- AS KCI
\ -
8.0. 0 30.000 D.D.m.CI-AS NaCl
” k
40
20
0
b
10
2‘0
2‘5
Tlme(day5)
Fig.5. Dependence of recrystallizationrate of aragonite to calcite upon concentration of potassium and sodium chloride solutions. The recrystallizationrate increases with increasing concentration of chloride solutions.
PHYSICAL CHEMISTRY OF FORMATION OF CARBONATES
N
N
0
2:
0
3 6
2:
W
?
W
N
-
0
2
2: Y
6 mul
G
E: 2
-
ti Im
0
N W
163
-
tl Im
I-
d
I
TABLE VI VATERITE IN CONTACT WITH
Experiment
Vaterite
150
DISTILLED WATER CONTAINING VARIOUS CONCENTRATIONS OF MAGNESIUM IONS AND CALCIUM IONS1
Chemistry of solution
Distilled water
WeiRht of precipitate
Volume (mu
(g)
Temp. ("C)
150
2.5
23+2
Duration of experiment (days)
Mineralogy, intensities Aragonite
Calcite
0 1 9
42 4 0
loo+ lOOt
8 32
78 59 0
8
78 0 78 65 22 0 0
Vateritc
420 p.p.rn. Ca
150
2.5
2312
0
4 0
Vaterite
30 p.p.m. Mg
I50
2.5
2312
0
4 5 29 71 72
8 8 7
4
8 10 8
Vaterite
60 p.p.rn. Mg
150
2.5
23*2
5
1 71 80 32 1 0 1 71
90 32 1 Vaterite
240 p.p.rn. Mg
150
2.5
23*2
0 1 71 I05
321
4 17 36 72 4 4 5 13 68
Aragonite Vaterite
9 8
12 9 8
9 9 8 8
+
78 67
40 66
0
78 72 70
60 0
3 X
1
1
Intensities are used as a measure of relative abundance of aragonite, calcite, and coincident peak vaterite-aragonite.
%1
PHYSICAL CHEMISTRY OF FORMATION OF CARBONATES
165
SUMMARY OF PHYSICAL CHEMISTRY
Some of the reactions between aragonite and test solutions, described in this chapter, can be summarized as follows: ( I ) Addition of a common ion, calcium in this instance, increases the recrystallization rate of aragonite to calcite. (2) Recrystallization rate of aragonite to calcite is markedly affected by temperature. Increasing the temperature of test solutions speeds up the recrystallization rate, whereas lowering the temperature reduces the recrystallization rate of aragonite to calcite. (3) Addition of a high pH solution to a mixture of aragonite and calcium, that would normally recrystallize rapidly, retards recrystallization. This pH value (10.4), however, is much higher than that normally found in modern carbonate sediments. (4) If the weight ratio of aragonite to magnesium ions in solution is less than 804, recrystallization of aragonite to calcite by solution and reprecipitation does not take place. (5) Strontium ions are effective in preventing recrystallization of aragonite to calcite, but the Sr2+ concentration necessary is much greater than that which occurs in marine waters. (6) Potassium and sodium-chloride solutions increase the recrystallization rate of aragonite to calcite over that of aragonite in distilled water. CONCLUSIONS
Lack of detectible recrystallization of metastable carbonate minerals in unconsolidated modern carbonate sediments may be attributed to the high concentration of magnesium ions in interstitial waters. If magnesium-ion concentration persists, the preserved metastable carbonate particles should be cemented by aragonite. This cementation by aragonite will preserve original textures and prevent large-scale recrystallization by aragonite solution and reprecipitation as calcite. Solid-state recrystallization of aragonite to calcite should preserve original chemistry such as Sr2+/Ca2+,12C/13C, and 1 6 0 / 1 * 0 ratios. These ratios should be useful in interpreting ancient depositional environments. In the case of aragonite solution and calcite precipitation, however, the resulting chemical ratios can be significantly altered as a result of changes of ion ratios in the interstitial waters. Preservation of aragonite in carbonate sediments for long periods favors formation of dolomite. This is particularly true in those environments where brines are concentrated at the surface by evaporation, the Mg/Ca ratio increases as a result of calcium carbonate precipitation, and brines percolate through aragoniterich sediment.
166
W. H. TAFT
ACKNOWLEDGEMENTS
Financial support for this work was provided principally by National Science Foundation Grants G- 19772 and GP-2527. Assistance of Catheryn MacDonald who did much of the laboratory work is gratefully acknowledged.
REFERENCES
BATHURST, R. G. C., 1959. Diagenesis in Mississippian calcilutites and pseudobreccias. J. Sediment. Petrol., 29: 365-376. CAROZZI,A. V., 1961. Reef petrography in the Beaverhill Lake Formation, Upper Devonian, Swan Hills area, Alberta, Canada. J. Sediment. Petrol., 3 1 :497-5 13. G. V., 1956a. Solubility of calcite, dolomite, and magnesite and mixtures of these CHILINGAR, carbonates. Bull. Am. Assoc. Petrol. Geologists, 40:2770-2773. CHILINGAR, G. V., 1956b. Note on direct precipitation of dolomite out of sea water. Compass, 34: 29-34. CHILINGAR, G. V . and BISSELL, H. J., 1963a. Formation of dolomite in sulfate-chloride solutions. J. Sediment. Petrol., 33: 801-803. CHILINGAR, G. V. and BISSELL, H. J., 1963b. Note on possible reason for scarcity of calcareous skeletons of invertebrates in Precambrian formations. J. Paleontol., 37: 942-943. CLOUDJR., P. E., 1962. Environment of calcium carbonate deposition west of Andros Island, Bahamas. U.S.,Geol. Surv., Profess. Papers, 350: 1-1 38. DEBOO,P. B., 1961. A preliminary petrographic study of beach rock. Proc. Natl. Coastal Shallow Water Res. Conf:, Ist, 1961, pp.456458. DURHAM, J. W., 1950. 1940 E. W. Scripps Cruise to the Gulf of California. Part 2: Megascopic paleontology and marine stratigraphy. Geol. SOC.Am., Mem., 43: 216 pp. ERENBURG, B. G., 1961. Artificial mixed carbonates in the CaC03-MgC03 series. J. Struct. Chem. (U.S.S.R.) (Eng. Transl.), 2: 178-182. GRAF,D. L. and GOLDSMITH, J. R., 1956. Some hydrothermal syntheses of dolomite and protodolomite. J. Geol., 64: 173-186. HARBAUGH, J. W., 1960. Petrology of marine bank limestones of Lansing Group (Pennsylvanian), southeast Kansas. Geol. Surv. Kansas, Bull., 142: 189-234. ILLING, L. V., 1964. Penecontemporary dolomite in the Persian Gulf. Bull. Am. Assoc. Petrol. Geologists, 48: 532-533. JAMIESON, J. C., 1953. Phase equilibrium in the system calcite-aragonite. J. Chem. Phys., 21: 1385-1 390. KITANO, Y .and HOOD,W. H., 1961.Effect of organic material on the polymorphic forms ofCaCO3. Geol. SOC.Am., Spec. Papers, 72: 86-87. LOWENSTAM, H. A., 1954. Factors affecting the aragonite/calcite ratios in carbonate-secreting organisms. J. Geol., 62: 284-322. LUCIA,F. J., WEYL,P. K. and DEFFEYES, K. S., 1964. Dolomitization of Recent and Plio-Pleistocene sediments by marine evaporite waters on Bonaire, Netherlands Antilles. Bull. Am. Assoc. Petrol. Geologists, 48: 535-536. MACDONALD, G. J. F., 1956. Experimental determination of calcite-aragonit? equilibrium relations at elevated temperature and pressures. Am. Mineralogist, 91 : 744-736. MURRAY,R. C., 1960. Origin of porosity in carbonate rocks. J. Sediment. Petrol., 30: 59-84. RUSSELL,R. J., 1961. Origin of beach rock. Proc. Natl. Coastal Shallow Water Res. Con$, Ist, 1961, pp.454-456. SCHMALZ, R. F., 1963. Role of surface energy in carbonate precipitation. Geol. SOC.Am., Spec. Papers, 76: 144. SHINN,E. A. and GINSBURG, R. N., 1964. Formation of Recent dolomite in Florida and the Bahamas. Bull. Am. Assoc. Petrol. Geologists, 48: 547.
PHYSICAL CHEMISTRY OF FORMATION OF CARBONATES
167
SIEGEL, F. R., 1961. Factors influencing the precipitation of dolomitic carbonates. Geol. Surv. Kansas, Bull., 152: 127-158. F. G. and HOWER, J., 1961. Mineralogy and early diagenesis of carbonate sediments. STEHLI, J . Sediment. Petrol., 31: 358-371. J. W., 1964. Modern carbonate sediments of southern Florida, TAFT,W. H. and HARBAUGH, Bahamas, and Espiritu Santo Island, Baja California: a comparison of their mineralogy and chemistry. Stanford Univ.Publ., Univ. Ser., Geol. Sci.,8: 1-133. WRAY,J. L. and DANIELS,F., 1957. Precipitation of calcite and aragonite. J . Am. Chem. SOC.,79: 203 1-2034.
Chapter 4 CHEMISTRY OF DOLOMITE FORMATION K. JINGHWA HSU University of California, Riverside, Calif. (U.S.A.)
SUMMARY
Chemical experiments under atmospheric conditions so far have not yielded any unequivocal answers on the stability of dolomite. The possibility that nesquehonite or hydromagnesite might be the stable magnesium carbonate at 25 "C and 1 atm. in the system MgC03-COz-HzO has added further complications. Unless further experimentation proves the contrary, the possibility exists that the stability of dolomite in the system C~CO~-M~CO~-COZ-HZOat 25°C and'l atm. is related not only to temperature and pressure, but also to the partial pressure of
coz.
The geologic occurrence of magnesium-bearing carbonates in Recent sediments is somewhat puzzling. The common occurrence of dolomite in ancient carbonate rocks, however, indicates that dolomite, rather than a mineral pair, is the stable phase under the low temperature and pressure conditions of carbonate diagenesis. The possibility that the calcite-hydromagnesite pair might represent a stable assemblage at 25°C and 1 atm. and extremely low pcoZ in the system CaCO3MgCO,-COz-HzO has been suggested-by the theoretical considerations and by experimental data. This tentative conclusion is not ruled out by the field evidence. Experimental evidence on the solubility of dolomite is controversial. The composition of the ground waters in dolomites is such that the writer believes the highest reported values (Kdr 1O-l') are more nearly correct than the lower values. This interpretation is not accepted by those who question whether equilibrium has been established or even approximated between a ground water and the solid carbonate phases of its host rocks. The controversy on the solubility of dolomite will probably not be resolved until dolomite is synthesized under controlled atmospheric conditions. Inasmuch as the solubility of dolomite is not known, the question whether any natural water (such as normal marine sea water) is saturated with dolomite cannot be satisfactorily answered. Experimental results on the composition of solution at dolomite-calcite-solution equilibrium differ radically, and deductions from such results have led to controversies. Nevertheless, all experimental results as well as deductions on the basis of ground water composition studies suggest that the Kdz value is less than 1 at room temperatures and atmos-
170
K. J. HSU
pheric or near-surface pressures. Paradoxically, sea water with a magnesium/ calcium-concentration ratio of 5.3 is apparently not dolomitizing. The reason is not clear, although alternative explanatidns have been suggested.
INTRODUCTION
The origin of dolomite involves two different problems. First of all, the chemical condition must have been such that the mineral dolomite could be formed as a stable phase. Secondly, the geologic history of a region must have permitted the chemical condition for the formation of dolomite mineral to persist long enough for sufficient quantity of the mineral dolomite to be formed in order to constitute a dolomite rock, or “dolostone”. This chapter is only concerned with the chemical problem of dolomite formation. Chemical experimental results are required to define specifically the conditions (temperature, pressure, chemical potentials of the various components in solution, etc.) under which the dolomite mineral can be formed. Unfortunately, experimental studies pertaining to dolomite formation under room temperatures and atmospheric pressures have not been very successful. Those who attempted to determine the solubility by dissolving dolomite in aqueous solutions have given widely divergent results; the solubility product of dolomite at 25°C and 1 atm., for example, as determined by the various experiments, ranges from 10-17 to 10-20, or a difference of three orders of magnitude! Deductions on the basis of controversial experimental data led, at times, to conflicting opinion. Further confusion arose because the occurrence of dolomite is not always what might be predicted on the basis of experimentation. This chapter is a review of the present status of our knowledge of the chemistry of dolomite formation under the relatively low temperatures and pressures of sedimentary and diagenetic conditions. The theoretical discussions begin with a consideration of the conditions of equilibrium as given by GIBBS(1875-1878) in his collected works, which form a basis for further theoretical deductions. A review of experimental work follows next. Finally, the geologic evidence pertaining to the chemistry of dolomite formation is presented.
-
A THREE-FOLD PROBLEM
-
Three questions may be asked regarding the chemistry of formation of the mineral dolomite. (I) Whether the double salt dolomite rather than a pair of single salts, calcite-magnesite, calcite-nesquehonite, or calcite-hydromagnesite, is the stable phase under a given temperature and pressure condition?
171
CHEMISTRY OF DOLOMITE FORMATION
(2) Whether the mineral dolomite could be precipitated from a solution of a given composition under a given temperature and pressure condition? (3) Whether the mineral dolomite should replace the mineral calcite (or aragonite) when a solution of a given composition at a given temperature and pressure is in contact with a solid phase of calcium carbonate? These three questions should be answered separately. The often-repeated phrase in geologic literature “conditions favorable for the formation of dolomite” is not meaningful unless one specifies the mode of formation.
STABILITY OF DOLOMITE
Theoretical discussions of conditions of equilibrium
GIBBS(1875-1878, p.63) stated that the variation of energy of any homogeneous part of variable chemical composition of a given mass is: dE
=
TdS - pdV
+ pldml -k pzdmz + . . . + pndmn
(1)
Where E denotes the total energy of the homogeneous part; T=its absolute temperature; S=its entropy; p=its pressure; V=its volume; ml, mz, . . mn are the quantities of the various substances; and pi, pz, . . . pn denote the chemical potentials of the various substances or the differential coefficients of E taken with respect to ml, mz, . . . md. If, for example, the whole mass consists of three homogeneous parts each consisting of the same two components, the variation of the energy of the system is expressed by dE’ d E ’ dE“’, if one distinguishes the letters referring to the different parts by accents. GIBBS(1875-1878, p.64) stated that the general condition of equilibrium requires that:
.
+
dE‘
+
+ dE” + dE”’ b 0
(2)
or:
To satisfy equation 3, the necessary and sufficient conditions of equilibrium are: The chemical potentials are intensive quantities: they can be expressed in J/g, or J/mole. Gibbs used the chemical potentials in terms of J/g; consequently, molecular-weight terms are involved in many of his equations. The chemical potentials are expressed here in terms of J/mole.
1
172
K . J. HSU
If the whole mass consists of three homogeneous parts (the first part consists of a substance s1, the second part of s2, and the third part of a substance s3 which is composed of s1 and s2 combined in the ratio l / l ) , then conditions of equilibrium are (GIBBS,1875-1 878, p.67):
On considering the reaction: CaC03 (calcite)
+ MgC03 (magnesite)
CaMg(CO3)z (dolomite)
(A)
at relatively low temperatures and pressures, when dolomite ideally does not contain CaC03 and MgC03 as separately variable components, the conditions of equilibrium are as follows: T' = T'= T"
P'
= P" = P"'
Y'CaCO,
ip"MgC03
p"'CaMg(C03)2
where ~'caco3.,U"MgC03 and ,U"'CaMg(C03)2 are the chemical potentials of the CaC03 in calcite, MgC03 in magnesite, and CaMg(CO& in dolomite, respectively. If calcite and magnesite are to form dolomite spontaneously, under a given T and p:
+
> p"'CltMg(C03)2
(7) Inasmuch as chemical potentials of those solid phases are a function of temperature and pressure only, and are independent of other variables, the stability of dolomite in the system CaCOs-MgCO3 depends thus upon temperature and pressure only. A complication arises, however, because of the uncertainties regarding the stability of magnesite. Free-energy calculations suggested that magnesite rather than nesquehonite is the stable magnesium carbonate phase at a temperature of 25 "C and a pressure of 1 atm in the system MgC03-H20 (GARRELS et al., 1960). Evidence on the basis of synthesis experiments suggested the contrary. KAZAKOVet al. (1957) repeatedly synthesized nesquehonite or hydromagnesite at room temperatures (1 5-24 "C) and atmospheric pressures, but failed to obtain magnesite under such conditions. Hydrothermal experiments by SCHLOEMER (1 952) also suggested that nesquehonite is the stable phase at temperatures below 80°C, above which, depending upon the Y'CaCO3
p"MgC03
40001-
173
CHEMISTRY OF DOLOMITE FORMATION
A
350°
:250°
0
Brucite 0
M \
Moqnesite
..
I w
--
N e s q u e honite 500
1,000
1,500 2,000 2,500 PRES'URE (ATM)
3,000
3,500
4,000
Fig.1. Stability of magnesite. (Modified after SCHLOEMER, 1952.). Hydrothermal experiments by Schloemer suggested that nesquehonite is the stable phase containing MgCO3 at room temperatures and atmospheric pressures. The univariant curve defining the equilibrium MgCOq8) 3Hz0 = M ~ C O ~ . ~ H ZisOdetermined (~) by experimentally determining the hydration temperature of nesquehonite at various pressures. The possibility of errors introduced by sluggishness of the reaction at low temperatures cannot be ruled out. That nesquehonite is the stable magnesiumcarbonate phase at room temperatures and atmospheric pressures is also indicated by the syntheet al. (1960), sis experiments of KAZAKOV et al. (1957). Free-energy calculations by GARRELS however, suggested that magnesite rather than nesquehonite is the stable phase in the system MgC03-H20 at 25 "C and 1 atm. total pressure. Crosses indicate runs in which the stable solid phase is nesquehonite; triangles, magnesite; and spheres, brucite.
+
confining pressure effect, nesquehonite may dehydrate to form magnesite and water (Fig. 1). If nesquehonite, rather than magnesite, is the stable carbonate in the presence of water, the following reaction must be considered:
+
CaC03 (calcite) MgC03.3HzO (nesquehonite) 3Hz0 (dolomite)
+
CaMg(CO3)z (B)
The conditions of equilibrium are:
where
and , U H ~ O represent the chemical potentials of MgC03. 3Hz0 in nesquehonite and that of water, respectively. In such a case, the stability of dolomite at room temperatures would be not only a function of T and p, but also that of the chemical potential of the water. $'MgC03.3H20
174
K. J. HSU
A still further complication arises because hydromagnesite could be the stable magnesium carbonate phase of the system MgC03-COz-HzO at room temperatures and very low pco, (KAZAKOV et al., 1957; GARRELS et al., 1960). If so, the following reaction must be considered:
+
4CaC03 (calcite) M ~ ~ ( C O ~ ) ~ ( O H ) Z .(hydromagnesite) ~HZO C02 e 4CaMg(CO& (dolomite) 4H20
+
The condition of equilibrium at any given T and p , would then be: T = T' = T" = T"' p = p' = p" = P"' 4p'CaC03
+
p"Mgp(C03)3(OH)2.3H20
+
+ pC02*4p"'CaMg(C03)2 + ~ P H , o
(C)
(9)
where ~ " M ~ ~ ( C O ~ ) ~ ( O H ) Zand . ~ H pcoZ ~ O represent the chemical potential of M ~ ~ ( C O ~ ) Z ( O H )in~ .hydromagnesite ~HZ~ and that of the C02, respectively. The question whether calcite-hydromagnesite pair or dolomite represents a stable phase at room temperatures is related, therefore, not only to T and p , but also to the chemical potential of water and to the partial pressure of COZ. Deductions on the basis of solubility experiments
The chemical potential of a one-component pure substance, expressed in J/mole is equal to its molar Gibbs Free energy, F. The change of free energy of the reaction A can thus be expressed by AFA, which is:
AFA = F"'
- (F'
+ F")
(10)
where F', F", and F"' represent molar free energies of calcite, magnesite, and dolomite, respectively. Equations 7 and 10 show that AFA must be negative if dolomite is to be formed from calcite and magnesite spontaneously at any given T and p . The AFA is related to solubility constants through a consideration of the following equilibria of calcite, magnesite, and dolomite with their saturated solutions: CaC03 (calcite)
s Ca2+ + CO&
MgC03 (magnesite)
zMgz+ + cos2-
CaMg(CO3)z (dolomite)
Caz+
+ Mgz+ + 2C0s2-
(D) (E) (F)
The free energy of a solution, F, at any given T and p , is related to,the activity of the ions, a, in solution by the relation (LEWISand RANDALL,1923, p.291):
F = F" -l- R T l n a
(1 1)
where F" is the free energy of a solution at an arbitrarily chosen standard state.
175
CHEMISTRY OF DOLOMITE FORMATION
Inasmuch as the free energies of the solids are equal to the free energies of their saturated solutions (FCa2+C0:-, FMg2+co:-, Fca2+Mg2+(co:-)2) at any given T and p, then:
F'
=
FCa'+Co:-
=
F"ca2+
+ Poco:-
f R T In Kc
F" = FMg2+co,2- = F0Mg2+-/ F"c0:- $- R T In Km
F"' = Fca2+Mg2+(c0:-), = FoMg2++ F"Ca'+
+ 2F"co:-
(12) (13)
-/ RTln Kd (14)
where Foca2+,FoMg2+and F"CO:- represent the free energies of Ca2+, Mg2+, and ions of a solution at an arbitrarily chosen standard state, and K,, Km, and Kd represent the equilibrium activity products (or solubility constants) of calcite, magnesite, and dolomite, respectively, at any given T and p. Thus, on substituting equations 12, 13, and 14 into equation 10, one obtains the condition of stability of dolomite, i f C032-
AFA = RTln-
Kd c40) Molecular type parafins naphthenes aromatics asphaltics
31 10 15
20 24
100
30 49 15
6 100
living things and petroleum. These substances have also been found in Recent and ancient sediments, suggesting that they find their way into petroleum purely by an accumulation process with only minor changes in chemical composition. The first structures from living things identified in crude oils were porphyrin derivatives of chlorophyll and hemin, which are the green plant and animal blood pigments, respectively. These were found by TREIBS in 1934. He found the chlorophyll-derived porphyrins to be about 20 times more numerous than those from the hemins. This suggestedthat crude oil originated primarily from plant life. Later, OAKWOOD et al. (1952) concentrated the optically active fraction of crude oils and found it to be a crystalline hydrocarbon with several naphthene rings. Optically active compounds have never been formed except by living things. This was an added evidence that a life process was involved. More recently, BENDORAITIS et al. (1963) isolated from petroleum a whole series of isoprenoid hydrocarbons, and MAIRand MARTINEZ-PICO (1962) isolated a hydrocarbon with the steroid nucleus. Both the isoprenoid and steroid structure are common in living things. The presence of hydrocarbons in living things has been known for some time. CHIBNALL and PIPER(1934) made the most detailed studies of paraffin hydrocarbons in insects and plant waxes. They were the first to discover a predominance of alkanes with odd carbon number chain lengths in the c 2 5 - c 3 7 range. WHITMORE (1945) postulated from his studies of the hydrocarbons in kelp that the quantities of hydrocarbons formed by life processes were sufficient to account for all the peand GERARDE (1961) published troleum in the world. More recently, GERARDE a detailed summary of all the hydrocarbons known to be in living organisms. Among the paraffin hydrocarbons, methane is the most common and is produced
228
J. M. HUNT
primarily in marshes where bacteria are metabolizing organic matter. No hydrocarbons from ethane through octane (CZ-CS)are known to be formed biologically, except possibly heptane. Paraffin hydrocarbons containing nine or more carbon atoms, particularly the waxes in the molecular weight range c23-c37, are quite common in nature. Naphthenes with less than ten carbon atoms do not occur in living organisms. Most of the cycloparaffins occur as unsaturated terpenes ( C ~ Hl6). O The naturally occurring aromatic hydrocarbons start with ten carbon atoms and go up into the higher molecular weight ranges. The most common is paracymene which is widely distributed in spices. The presence of high molecular weight hydrocarbons in marine organisms has been studied by BERGMANN (1 949, 1963), who first observed that the unsaponifiable fraction of invertebrate lipids was higher in the more primitive animal forms. This suggested that waxes, sterols, and hydrocarbons are most prominent in the lowest and most primitive forms of life. BLUMER et al. (1964), BLUMER and THOMAS (1964), and BLUMER and OMAN(1965) have isolated pristane and a whole series of hydrocarbons related to phytol from marine zooplankton. The first isolation of liquid hydrocarbons from Recent sediments was by SMITH(1954) who found a series of paraffin, naphthene, and aromatic hydrocarbons heavier than c14 in Gulf Coast muds. He was able to date them by radiocarbon methods at about 10,000 years. A more detailed study by MEINSCHEIN (1961) showed a large number of hydrocarbons having more than 14 carbon atoms to be present in Recent sediments. It should be emphasized that the hydrocarbons identified by the aforementioned workers in living things and in Recent sediments represent only a very small fraction of petroleum in the higher molecular weight range (above c14). SOKOLOV (1957) and VEBERand TURKELTAUB (1958) stated that their studies of hydrocarbons from the sediments of the Caspian Sea and Black Sea, which are rich in organic matter, showed no hydrocarbons in the CZ-c14 range. They pointed out that the hydrocarbons in Recent sediments cannot represent petroleum because the missing fractions up to c14 constitute up to 50% or more of many crude oils. EMERY and HOGGAN (€958) had previously reported finding a total of less than 1 p.p.m. of these hydrocarbons in sediments of the basins off the California coast. J. G. Erdman (personal communication, 1962) found only methane and heptane in the Cl-C, range of Recent sediments, whereas in ancient sediments he found all the saturated hydrocarbons including pentanes: hexanes, heptanes, etc. ERDMAN et al. (1958) had previously reported that the low molecular weight aromatic hydrocarbons, benzene and the xylenes, also are absent from Recent sediments. DUNTONand HUNT(1962) found the C4-cS hydrocarbons to be absent from 21 Recent sediment samples from Venezuela, Texas, Cuba, California, and Norway. Twenty-nine ancient sediment samples ranging in age from Precambrian to Miocene, however, yielded c 4 - c S hydrocarbons in amounts ranging from 1 to
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
229
over 800 p.p.m. These studies show that hydrocarbons lighter than nonane (Cg) are generally absent in Recent sediments. It has also been found that there are fewer heavy hydrocarbons in Recent sediments than in ancient sediments. HUNT(1961) analyzed 55 Recent sediment samples from six different areas and found only one of them to contain as many hydrocarbons above C14 as the average of 1,000 ancient sediments. Most of the Recent sediments contain only about 1/5 as many hydrocarbons as the ancient sediments. In summary, it appears likely that some of the hydrocarbons in the high molecular weight range of petroleum are synthesized by living organisms and eventually become crude-oil accumulations with only minor changes. All paraffin, naphthene and aromatic hydrocarbons containing less than nine carbon atoms (except methane and heptane), however, are not synthesized by living organisms, and are not found in Recent sediments. Consequently, these must be generated in the sediments. Also, the fact that Recent sediments contain fewer hydrocarbons above Cg than ancient sediments suggests that part of the whole molecular weight range of hydrocarbons is formed from organic matter in the sediments. Generation of hydrocarbons from organic matter
The basic substances of plant and animal material are the proteins, carbohydrates, and lipids. Higher plants also contain lignin, a high molecular weight aromatic compound. Lignin comprises about 15-20 % of the total terrestrial plant substance on a dry weight basis and would be the major contributor of aromatic structures to petroleum. The proteins, which are the chief source of nitrogen in organic sediments, are complex polymers of amino acids, Cellulose, the most important carbohydrate, is a fundamental constituent of cell walls. Lipid is a general term which includes waxes, fats, essential oils and pigments. Many of the pigments are pure hydrocarbons and can be incorporated in crude oils with only minor chemical changes. SILVERMAN (1962) pointed out that the 13C/12C isotope ratios of petroleum and various organic materials point to the lipids as the primary source of petroleum. In chemical composition the lipids are closest to petroleum as can be seen from Table 11. Any of these constituents may be potential sources of hydrocarbons until proven otherwise. Bacteria, which are common in the first few feet of most sediments, bring about the initial decomposition 6f organic matter. From 10-50% of the organic matter is converted into bacterial cell material. Under aerobic conditions the free products are water, carbon dioxide, and sulfate, phosphate and ammonium ions. Products formed are similar under anaerobic conditions except that sulfur is eliminated as hydrogen sulfide and methane and hydrogen are formed (ZOBELL, 1959). One significant difference between carbonate and clay sediments concerns the depth at which bacterial activity may occur. LINDBLOOM and LUPTON(1961)
230
J. M. HUNT
TABLE I1 AVERAGE CHEMICAL COMPOSITION OF NATURAL SUBSTANCES
Elemental composition in weight %
carbohydrates lignin proteins lipids petroleum
C
H
44
6 5 7 10 12-15
63 53 80 82-87
S
0.1 2 0.1-5
N 0.3 16 0.1-0.5
0 50
31 22 10 0.1-2
found that bacteria living on the organic matter in carbonate muds from Florida and Cuba practically died out within the first five feet of sediments. Clay muds from areas such as the Orinoco Delta and the Gulf of California, however, contained active bacteria at much greater depths. In the former case viable bacteria were found to a depth of about 150 ft. Lindbloom and Lupton suggested that the extreme reducing conditions and the high H2S content associated with carbonate muds such as those from Florida Bay may limit bacterial growth. The average Eh of eleven shallow cores from carbonate muds of Florida Bay and the Gulf of Batabano was -200 mV, whereas some Orinoco Delta clay sediment had a positive Eh even at great depth. The iron associated with clay sediments utilizes H2S to form sulfides, but in pure carbonates relatively free of iron, there is a build-up in H2S content which remains in the sediments even at great depths. This H2S has been found in ancient carbonates which may have little or no organic matter. It may also be a factor in the high suifur content of many oils associated with carbonates. KREJCI-GRAF (1963) stated that the commonly asphaltic nature and high sulfur content (several percent) of oils ,associated with calcareous rocks implies a different mode of origin than that of low (usually under 1 %) sulfur oils from clay sediments. As the organic matter is buried deeper in sediments, the bacterial activity becomes less important and the conversion of organic matter to hydrocarbons proceeds through thermal or catalytic degradation. Catalytic activity requires intimate contact between the organic matter and the mineral surface. Here there appears to be significant differences between carbonate and clay muds. GORSKAYA (1950) noted that as the particle size of Recent clastic sediments decreased, the percent of organic carbon, the total bitumens and the hydrocarbons all increased (Table III). In a study of the Viking Shale, HUNT(1962) found a three-fold increase in the organic content in going from siltstone to clays having particles less then 2 p in diameter as shown in Table IV. The organic matter in clays, associated with the finest particle size, is, therefore, in intimate contact with the mineral surfaces.
23 1
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
TABLE I11 ORGANIC MA'ITER OF RECENT CLASTIC SEDIMENTS
(After GORSKAYA, 1 950) Sediment
organic matter (weight %)
Weight % in organic matter total bitumens' hydrocarbons
sands silts clay muds
0.77 1.15
1.5 2.1
1
1.80
2.8
0.043 0.096
0.141
Organic matter soluble in organic solvents.
On the other hand GEHMAN (1962), in a study of 346 ancient limestone samples, found the carbonate muds to contain 0.18 % organic matter compared to 0.23 % for skeletal grains and 0.10 % for non-skeletal grains. Gehman also found that the organic compound, quinoline, in aqueous concentrations up to 200 p.p.m. was readily adsorbed by the three principal clay minerals, namely, kaolinite, illite, and montmorillonite; whereas no adsorption occurred with lime-mud. Clays have been known for decades to be excellent catalysts in causing rearrangements of carbon groups in organic compounds. FROST(1945) was able to convert alcohols, ketones, and other non-hydrocarbon compounds to hydrocarbons at relatively low temperatures, such as 150-180 "C,in the presence of clays. He found that the montmorillonite- and illite-type clays were quite active, whereas the kaolinites were relatively inactive. More recently, WEISS(1963) reported the formation of cyclic and aromatic hydrocarbons from heating organic complexes of montmorillonites. A particularly interesting study is that of JURG and EISMA (1964), who found that heating behenic acid (C21H4sCOOH) at 200°C in the presence of bentonite with or without water yielded a series of paraffin and olefin hydrocarbons. It is significant that hydrocarbons were obtained in the presence of water, which would be TABLE IV VARIATION IN ORGANIC CONTENT WITH PARTICLE-SIZE IN VIKING SHALE
(After HUNT,1962) Particle size
Organic matter (average weight %)
232
J. M. HUNT
the natural state for oil generation. No hydrocarbons were obtained by heating without the clay. Although more studies of this type are needed, particularly with carbonate muds, it does appear that the clay shales have a distinct advantage over carbonates in generating hydrocarbons by catalytic processes. There is still the possibility for the catalytic generation of hydrocarbons because the small amount of clays is dispersed in many carbonate rocks. USPENSKIY et al. (1949) noted that the organic carbon in carbonate rocks is primarily associated with the clay minerals frequently present in such rocks. The author treated a sample of mud from Florida Bay with dilute hydrochloric acid to isolate the non-carbonate fraction. The latter was then analyzed for organic matter content and compared with the original mud. One sample containing about 15% of clay minerals was found to have 75 % of its organic matter attached to the small clay fraction and only 25 % to the large carbonate fraction. (1 95 1) noted a very clear relationship between USPENSKIY and CHERNYSHEVA the insoluble residue, presumably clays, in carbonate'rocks and the organic matter as shown in Table V. The total organic matter and the bitumen content, which includes hydrocarbons, increased with increasing insoluble residue content. In pure carbonates, where no clays are present, the possibility of catalytic formation of hydrocarbons is remote. The conversion of organic matter to hydrocarbons in pure carbonates is a thermal process. This suggests that somewhat greater depths of burial and longer periods of time are required to generate oil in carbonates than in clays. Consequently, carbonate source beds might not yield oil to reservoirs as early in the history of a sedimentary basin as would the clays.
TABLE V RELATIONSHIP BETWEEN ORGANIC MATTER AND INSOLUBLE RESIDUE OF CARBONATE ROCKS
(After USPENSKIY and CHERNHYSHEVA, 1951) Insoluble residue (weight %)
Organic matter (weight %)
Bitumen' (weight %)
4.3 10.2
0.06 0.15 0.28 0.49 0.70 0.93 2.36
0.015
15.5
24.5 57.9 66.1 72.8 1
0.021 0.034 0.034 0.046 0.05 1 0.052
Organic matter soluble in organic solvents. It contains the hydrocarbons.
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
233
MIGRATION OF PETROLEUM
The primary migration of petroleum involves the movement of oil and gas from the dense, low permeability source sediment into the porous, permeable reservoir rock. Secondary migration is concerned with the movement of petroleum within the reservoir rock. In considering carbonates as possible source rocks, it is important to compare the processes of primary migration as they might occur in carbonates and clays. The most plausible hypothesis is that as the sediments are deposited, the more deeply buried sediments lose their interstitial water under the forces of overburden pressure and compaction. WEEKS(1961) has estimated that from 15-20 billion barrels of fluid is expelled from each cubic mile of mud during compaction of a sedimentary basin. As the fluid passes out of the consolidating sediment it carries with it minute quantities of oil. On entering a porous reservoir rock, the physical and chemical conditions are believed to change sufficiently to cause release of the oil. As the oil droplets increase in size, they are unable to re-enter the fine, water-wet pores of the surrounding dense rock. This is purely a hypothesis and it does not explain how the oil migrates in the water, what portion of it moves with the water, or at what stage most of the oil leaves the source bed. The oil may travel in the form of droplets, as a colloidal dispersion, in solution, or in a gaseous form. HOBSON(1954) has discussed a mechanism by which oil globules may be squeezed between small pore openings, eventually making their way into the reservoir. E. G. BAKER(1962) has presented evidence on petroleum composition, which, according to him, supports the concept of the migration of oil as a dilute colloidal dispersion stabilized by natural soaps. MCAULIFFE ( I 964) made detailed studies on the solubility of hydrocarbons in water. His data suggested that hydrocarbon solubilities are sufficient to account for known oil accumulations. In most sedimentary basins calculations of the total quantity of water moved compared to the oil in place indicate that solubilities of hydrocarbons in water of 2-5 p.p.m. are sufficient to account for the oil fields. There are arguments against all of the proposed mechanisms. Migration of oil as globules would require distortion of the globule in order to move through the very fine pores of the source bed, and such distortion is resisted by the high interfacial tensions. About 50 times more soap or solubilizing material than hydrocarbon is needed for the formation of a colloid, and it is well known that such surface-active agents tend to be adsorbed by the host rock. For example, attempts to use soap solutions for the secondary recovery of oil have largely failed because the soap is adsorbed on the mineral surfaces before travelling very far. Migration either as a colloid or in pure solution does not explain why the oil separates out on entering a porous reservoir. Undoubtedly there are differences in the physical and chemical environment of the reservoir compared to the source bed, but just what these are and how they cause separation of the oil is not known.
234
J. M. HUNT
If oil migrates as fine globules or as colloids it would encounter more difficulty in moving through fine-grained carbonate source beds than through clays. Carbonate particles would not have the mechanical ability of clay particles to cause distortion of the globules and consequent squeezing through the sediment pores. Migration as a soap-stabilized colloid would be stopped by the presence of calcium and magnesium ions in the water. It is generally known that calcium ions in sand columns will tie up surface-active agents, and there is no reason why this would not happen in muds. Migration in solution without the aid of solubilizing organic material would probably occur as readily in carbonates as in clays. GINSBURG (1957) has pointed out that most of the water in carbonatemuds is lost in the first foot or two. WELLER(1959) agrees that very little compaction occurs in lime-muds. HOLLMANN (1962) showed evidence for the underwater consolidation of limestones, and observed that in relatively deep water off northern Italy the undersides of ammonites have impressions of irregularities of the underlying limestone beds. This indicates that the limestone beds were hardened and partly dissolved before the ammonites were laid down. The limestones consolidate mainly by cementation and recrystallization. It would seem from this that the migration of fluids from limestones would occur too early and over too short a depth interval to be an effective mechanism in carrying appreciable quantities of oil to a reservoir. Consequently, most of the oil in a carbonate rock would be locked in and would have to find its way out at some later stage of lithification. This could occur with fluid migration along fractures, solution paths and joints which (1962) observed are much more common in carbonates than in shales. GEHMAN that the ratio of hydrocarbons to organic matter in limestones was much higher than that in shales. This is consistent with the idea that limestones tend to lock in their hydrocarbons and release them with much more difficulty than do the shales. There are other explanations for this, however, which will be considered later. CHAYKOVSKAYA (1960) stated that according to some investigators the early lithification of carbonate muds makes them incapable of giving up bitumens to surrounding formations. Nevertheless, there are evidences of molecular migration within carbonate source beds which are quite numerous and convincing. Chaykovskaya pointed out that bitumens move into the numerous fractures and caverns that are formed by the circulation of underground water through the carbonate rocks, which also increases primary porosity. She concluded that several of the carbonate formations in the Turukhansk and Noril’sk district of the Soviet Union are characterized by high bitumen content. These’bitumens were formed within the carbonate source beds and redistributed themselves in minor caverns, pores and fractures. Chaykovskaya also agreed with Gehman that pure carbonate formations contain a relatively small quantity of organic matter, a large part of which consists of hydrocarbons. It should be emphasized that there are many argillaceous limestones and calcareous shales having mineral compositions between those of the clays and
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
235
carbonates. These are even less understood with respect to their compaction characteristics and ability to release fluids to the reservoirs. Many of these hybrid sediments have very high organic contents (HUNT,1961; BITTERLI, 1963). Some of these, such as the Duvernary Formation of Canada and the LaLuna Formation of Venezuela, appear both chemically and geologically to be source rocks.
EXAMPLES OF CARBONATE SOURCE ROCKS
Recently, OWEN(1964) reviewed the geological concepts favoring carbonates as being source rocks. He stated that the stratigraphic and structural habitats of many oil and gas pools in carbonate rocks indicate indigenous origin of their hydrocarbons. There are many oil-producing areas where carbonate rocks are by far the dominant lithology. Some of the important oil occurrences are discussed in this chapter. The Williston Basin, U.S.A.
This basin covers an area of more than 100 sq. miles and contains a Devonian marine carbonate section more than 1,000 ft. thick (BAILLIE,1955). The strata consist of an assemblage of limestones, dolomites, evaporites and minor amounts of shale. Commercial oil is found in the predominantly carbonate strata of the Saskatchewan group, although both oil shales and asphalt stains are present throughout many parts of the Middle and Upper Devonian. For example, at the base of the Elk point group in northwestern North Dakota and eastern Montana, there is a dark colored, dense limestone that was deposited under euxinic conditions that favored preservation of organic matter. Oil shows and staining are common on fractured surfaces, suggesting that the oil is indigenous, and that the dark limestone can be considered a source rock. Here again, however, it could be argued that clays are contributing some oil, because argillaceous limestones and dolomites are common to both the Middle and Upper Devonian sections. Nevertheless, this does represent an oil-generating area of predominantly carbonate facies. Many of the carbonates of both the Elk Point and Saskatchewan groups are pale to dark brown limestones and dolomites with dark grey carbonaceous shale laminae in places, and oil staining and bitumens are common throughout the section. Abqaiq-Ghawar oil j e l d , Saudi Arabia
The largest oil field in the world, Abqaiq-Ghawar, is on a structural accumulation more than 140 miles long and produces from an oil column reaching a maximum vertical thickness of 1,300 ft. (ARABIAN-AMERICAN OIL COMPANY STAFF,1959). The main producing interval is the Arab-D member in the upper part of the Juras-
236
J. M. HUNT
sic Jubaila formation. The Jubaila consists of 1,200ft. of fine-grained limestone with subordinate calcarenite, limestones and dolomite. The Arab-D formation consists of calcarenite, fine-grained limestone and dolomite with interbedded anhydrite members (560 ft.). This is overlain by another 500 ft. of limestone and dolomite with an anhydrite cover. Above the anhydrite at the base of the Arab-D member the sediments contain only oil shales and minor staining. Most of the oil production found in the first 240 ft. of the Upper Jubaila Formation is below the anhydrite. The Arabian-American Oil Company staff, who have probably studied this field more intensively than any other group of individuals, believe that the Ghawar oil originated in the Upper Jubaila and Arab-D sediments. This is based partly on the apparently capricious distribution of oil and water in porous units of the Middle and Lower Jubaila. The volume of these porous units is roughly proportional to the amount of calcarenite in the formations. This is probably one of the most clear-cut geological examples of carbonate source rocks. Other Middle East ,fields
Other possible carbonate source beds in the Middle East include the Middle Cretaceous to Oligocene limestones and chalk of Iraq, Iran and southeast Turkey with oil in associated reef complexes and fractured limestones (BAKERand HANSON, 1952). Also, the oil fields of southwest Iran produce from the Upper Asmari Limestone which is believed to contain indigenous oil. The Asmari Limestone is 700-1,500 ft. thick and has reef characteristics in places. Both the Miocene and Oligocene components of the Asmari are richly organic. The 60-mile long Kirkuk, a billion barrel oil field in northern Iraq, is another good example of a Middle Eastern oil field with carbonate source rocks (DUNNINGTON, 1958). The producing reservoir is made up of reef and globigerinal limestones of Middle Eocene to Lower Miocene age. Limestone and a salt bed overly it, and thick limestones and marlstones underly it. Miscellaneous examples
There are other examples of oil occurrence in carbonate rocks but in many of these an overlying or underlying shale is a more likely source. One of the most common examples of this is oil occurring at unconformities where shales overly carbonates. Porosity in such carbonates is frequently due to erosion and solution weathering. This provides an excellent reservoir for oil migration from overlying clay muds. Typical examples are the Rogers City, Traverse, and Dundee Limestones of the Michigan Basin and the Trenton Limestone of Michigan and western Ohio. Another is the Simpson Shale acting as a source for the Ellenburger Limestone of the Permian Basin of Texas and New Mexico. MILLERet al. (1958), in a detailed study of the oil in the Maracaibo Basin of Venezuela, concluded that the highly bituminous LaLuna Limestone was a
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
237
probable source for some of the oil in western Venezuela. The effective reservoir section of the Cogollo and La Luna'Limestones is about 1,800 ft. thick. BODUNOVSKVORTSOV (1 958) believed that the bitumens found in the lower Cambrian dolomitic limestones of eastern Siberia were indigenous. There are three carbonate suites, the Angar, Bulay and Bel, which represent about 800 m of limestones interbedded with anhydrite. The whole section is underlain by a thick dolomite sequence. BROD(1959) believed that the asphalts and bitumens found in inclusions of thick Paleozoic limestones and dolomites of the western part of the East Siberian platform are indigenous. There are probably many other examples of carbonate sediments believed to be source beds of oil. Those given here are suficient, however, to attest to the widespread distribution of carbonate sources. As previously mentioned, carbonate rocks contain at least 40 % of the world's oil, although they represent only 16 % of the sediments of the basins of continents and continental shelves compared to 50% for clay shales (WEEKS,1958). Some of the factors which favor formation of carbonate source rocks include the following: (I) It has been stated that the carbonates would lithify quickly and tend to hold in their hydrocarbons during the early stages of fluid migration from a basin. Many hydrocarbons are undoubtedly lost from clay muds during this period due to the lack of a sufficiently impermeable caprock. (2) Limestones are frequently associated with evaporites under conditions that are highly favorable to oil generation and accumulation. WEEKS(1961) cited a typical sedimentary sequence as beginning with a deep stagnant limy mud facies with limestones or dolomites around the flanking shelves. Cherts may occur in the deeper parts, followed by purer, partly recrystallized and dolomitized limestone facies. Isolated reefs facing the deep basin as well as patch reefs higher on the shelf are common. The sequence continues up with spreading evaporites-primary dolomites, anhydrites, and/or salt. Eventually evaporites spread over the entire central area of the basin. In such a cycle the organic matter which accumulated from the beginning eventually generates hydrocarbons on a vast scale. These are then trapped because of the presence of impermeable cover of evaporite deposits. Weeks cited about 20 examples of oil-producing basin sequences that go through some or all of these stages. (3) The hydrocarbons moving with the aqueous phase through fractures, fissures and primary.pores enlarged by solution would tend to be released to form oil globules on contact with the highly saline waters typical of carbonateevaporite sequences. This is speculative, of course, but the great variations in salinities could be a favorable factor in the oil-accumulation process. In summary, it appears that most carbonate source rocks associated with major oil accumulations, such as the huge Tertiary and Jurassic oil pools of the Middle East, are of this carbonate-evaporite sequence type favorable for the origin, migration and accumulation of oil.
238
J. M. HUNT
DISTRIBUTION OF ORGANIC MATTER IN CARBONATE SOURCE ROCKS
Geochemists have approached the identification of source rocks by making detailed studies of the various organic constituents in ancient sediments and finding out differences between oil-producing and non-producing regions. If one accepts the concept that petroleum originates from organic matter deposited with the non-reservoir sediments (dense carbonates) and migrates into reservoirs (reefs, oolites), then it is important to understand the distribution of the organic matter and hydrocarbons in the non-reservoir sediments. The distribution of organic matter in sediments varies widely and is significant in drawing conclusions about the probabilities of finding oil in a particular part of a sedimentary basin. Unfortunately, few studies of this type have been made in carbonate sequences. Much more common are studies of clays with minor amounts of carbonates. For example, RONOV (1958) made a detailed study of the organic carbon distribution in the Devonian sediments of the Russian platform. He found that, in general, the clays contained more organic carbon than the carbonates. His data are shown in Table VI with the organic carbon converted to organic matter by multiplying by a factor of 1.22 (see FORSMAN and HUNT,1958, for conversion factor). As might be expected, the coastal and open-sea environments contained most of the organic matter and the continental the least. Ronov also noted an interesting correlation between the occurrence of petroleum in Devonian reservoirs and the concentration of organic matter in associated non-reservoir rock. He found that all the petroleum was located in regions where the associated shales contained the higher organic contents, generally at least 1 % organic matter. In regions where the organic content of the shales was low (generally less than 0.5 %), no oil or gas was found. Inasmuch as the carbonates were intermixed with the clays, no conclusions can be drawn as to their effect on the oil accumulations. Also, Ronov did not make hydrocarbon analyses which are important in evaluating carbonate source rocks. TABLE VI WANIC MATTER AND ENVIRONMENT (DEVONIAN OF THE u.s.s.R.)
(After RONOV,1958) Environment
Weight % of organic matter1 carbonstes
days
continental, lagoonal coastal-marine open sea 1
Organic carbon times 1.22.
0.43 0.95 1.10
'
0.18 0.25 0.39
239
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
TABLE VII DISTRIBUTION OF HYDROCARBONS AND ORGANIC MATTER IN NON-RESERVOIR ROCKS
(After HUNT,1961) Rock type
Shales Wilcox, La. Frontier, Wyo. Springer, Okla. Monterey, Calif. Woodford, Okla. Limestones and dolomites Mission Canyon Limestone, Mont. Ireton Limestone, Alta. Madison Dolomite, Mont. Charles Limestone, Mont. Zechstein Dolomite, Denmark Banff Limestone, N.D. Calcareous shales Niobrara, Wyo. Antrim, Mich. Duvernay, Alta. Nordegg, Aka.
Hydrocarbons fP,p.rnJ
Organic matter (weight %)
180 300 400 500 3,000
1 .o 1.5 1.7 2.2 5.4
67 106 243 271 310 530
0.11 0.28 0.13 0.32 0.47 0.47
1,100 2,400 3,300 3,800
3.6 6.7 7.9 12.6
The hydrocarbon analysis can be obtained by pulverizing the sediment sample and extracting the soluble organic matter with various organic solvents, such as ether or benzene. The soluble organic matter can be separated into two fractions, the hydrocarbons and the non-hydrocarbons (asphalts), by column chromatography (HUNT,1956; PHILIPPI,1956). Light hydrocarbons are lost in removing the solvent so that the molecular weight range starts a t about c14 and continues on to c40-c50. The asphalts are compounds containing nitrogen, sulfur and oxygen as well as carbon and hydrogen. The residual organic matter, which has sometimes been referred to as kerogen, has been described in some detail by FORSMAN and HUN? (1958). The distribution of the hydrocarbons and residual organic matter in some typical shales and carbonates is shown in Table VII. The hydrocarbon fraction represents petroleum that is disseminated in the source bed. In most sedimentary basins there is 20-100 times as much of this petroleum in the source beds than in the reservoirs. The high concentration of hydrocarbons and organic matter in rocks such as the Woodford, Duvernay and Nordegg Shales does not automatically make
240
J. M. H U N T
them good source rocks. It is possible that the organic content of this type of sediment is so high that it tends to act as a blotter, that is, it adsorbs hydrocarbons instead of releasing them to the reservoirs. The fact that some rocks such as the Mission Canyon limestones have a very low hydrocarbon content does not necessarily mean that they have released a considerable amount of hydrocarbons to reservoirs. The quantities of hydrocarbons that were originally present or have been gathered from any of these sediments is not known. Some estimates could be made by adding up the hydrocarbons in both reservoir and non-reservoir rocks of an entire sedimentary basin, but this figure would not include losses over geologic time. It is interesting to note that most of the limestones and dolomites have hydrocarbon contents comparable to those of the shales even though the organic contents are lower by a factor of 10. This emphasizes the aforementioned importance of hydrocarbon analyses. The low organic content of carbonates compared to shales in Table VII agrees with Ronov's data in Table VI. Recent carbonate sediments, however, have organic contents very similar to those of Recent clays (Table VIII). GEHMAN (1962) suggested that most carbonates lose organic matter faster than shales due to repeated exposure to meteoric waters. An alternative hypothesis by E. T. Degens (personal communication, 1964) is that the carbonates contain primarily proteinaceous organic matter which is hydrolyzed during recrystallization, whereas the clays contain primarily humic and lignitic organic matter which survives the period of compaction and diagenesis. This is summarized in Fig. 1 and 2. If a large part of the organic matter is lost in carbonate sediments early in their diagenesis, it still does not explain why the remaining organic matter is such an efficient generator of hydrocarbons. The ratio of hydrocarbons to organic matter as shown in Table VIII is far higher in ancient carbonates than in ancient shales. Unfortunately, the proportion of hydrocarbons lost from these two types of rocks is TABLE VIII DISTRIBUTION OF HYDROCARBONS AND ASSOCIATED ORGANIC MATTER IN RECENT AND ANCIENT SEDIMENTS
(After HUNT, 1961) Sediments
fiydrocarbons (p.p.m.)
clays (Recent)2 clays (ancient)2 carbonates (Recent)l carbonates (ancient)2 1 2
Gulf of Batabano, Cuba. Average of samples from several areas.
50 300 40 340
Organic matter (weight %) 1.5
2.0 1.7
0.2
'
24 1
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
[7 Amino
compounds
Carbohydrotes Organic solvent extract Organic residue( humicl
Ancient shole (mean total organic matter 1
-Ancient limestone (mean total organic matter) Shell Carbonate (Mylilus Cali fornianusl
Limestone (Florida Bay)
Clay (Son Diego Tmughl
Fig.1. Organic maaer content of Recent marine sediments. (After E.T. Degens, personal communication, 1964.) WEIGHT PERCENT IN CLAYS
CONSTITUENTS
WEIGHT PERCENT IN CARBONATES
85
Humus and lignin
5
10
Proteins Sugars and lipids
90
=\>y.dorv!si Compaction
Only 5-10% 6;ganic
of proteins\Recrystallization
matter lost
About 75%organic matter lost
Fig.2. Loss of organic matter in sediments.
not known. As previously mentioned, it may be that most of the hydrocarbons generated in carbonates are trapped in them by early lithification, whereas those in shales represent a remnant of a much greater amount that was generated and partially lost. One of the most detailed studies of the distribution of hydrocarbons in the source-reservoir facies of a geological section was made by D. R. BAKER(1962). He found a wide Yariation between the hydrocarbon and organic carbon contents of sediments of different lithologies from the Cherokee group of Kansas and Oklahoma. His data for the principal lithologies are summarized in Table IX. The range in hydrocarbon content from these different lithologies, which are in very close stratigraphic proximity, is nearly as large as for samples from all over the world as shown in Table VII. All of the lithologies presented in Table IX could have contributed some hydrocarbons to the Cherokee reservoirs. The most probable sources would be the limestones and gray shales. The underclays and greenish-gray shales have too
242
J. M. HUNT
TABLE IX MEAN ORGANIC COMPOSITION OF PRINCIPAL ROCK TYPES OF CHEROKEE GROUP OF KANSAS AND OKLAHOMA
(After D. R. BAKER,1962) Rock type
underclay and related rocks greenish-grayshales and related rocks limestone gray shale black phosphatic shale
Number of samples
Hydrocarbons (p.p.m.)
Organic carbons Hydrocarbons (weight %) organic c
9
19
0.34
1.06
43 11 31 19
31 91 129 2,920
0.31 0.19 1.52 7.94
1.26 4.12 0.92 3.88
*
10-2
low a hydrocarbon content to be effective contributors, whereas the phosphatic shale is so rich in hydrocarbons that it might not release them. Baker’s data verify the results obtained by other investigators previously mentioned by showing a very high ratio of hydrocarbons to organic carbon in carbonates. In discussing his results, Baker mentioned the problem of differentiating hydrocarbons which have migrated vertically into a presumed source bed from those which are indigenous. This is a knotty problem which clouds any interpretation of hydrocarbon distribution in sediments. Most comparisons of crude oil in reservoirs, however, show that there are chemical similarities over several miles horizontally within a formation, but marked differences can be observed in only a few hundred feet vertically. The data of BASS(1963) are typical in showing the composition of crude oil in the Rangely, Ashley Valley and Elk Springs pools in the Weber sandstone to be similar even though they span a horizontal distance of 50 miles. On the other hand, the oils in the Weber, Shinarump and Mancos Sands are entirely different even though they span a vertical distance of only 4,000 ft. (less than 1 mile). This suggests that the migration of most crude oils occurs within neighboring stratigraphic units and does not span the entire vertical section of the basin. NERUCHEV (1962) also has geochemical data, to be shown later, which indicate that most hydrocarbons in the source beds are indigenous.
GEOCHEMICAL TECHNIQUES FOR RECOGNIZING CARBONATE SOURCE ROCKS
The studies reported above have provided much valuable information on how hydrocarbons are distributed in sedimentary basins relative to oil and gas accumulations. Many petroleum companies have also developed empirical methods of
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
243
source-rock identification which are based partly on experience and partly on faith. The first of these empirical methods was developed by PHILIPPI (1956) and associates of the Shell Oil Company. They considered fine-grained sediments with indigenous oils to be oil-source beds, the source-rock quality being defined as the amount of hydrocarbons present per unit weight of dry rock. Rocks with less than 50 parts of indigenous hydrocarbons per million parts ofdry sediment were considered very poor sources, whereas those with over 5,000p.p.m. were considered excellent sources. The LaLuna Limestone of western Venezuela was regarded as an important oil source by this method. The hypothesis on which this technique is based is simply that if a finegrained sediment contains indigenous hydrocarbons, it means that the sediment was capable of generating hydrocarbons and, therefore, is a source rock. One cannot really define the sediment as an oil source, however, unless oil from it has accumulated in commercial quantities. This requires not only generation but also release of the hydrocarbons and their accumulation in a suitable porous trap. Assuming that the hydrocarbons extracted by the Shell technique are indigenous, the method does fulfill the first requirement of a source rock but not the others. In effect, it gives a picture of the distribution of hydrocarbons in a sedimentary basin, and one must assume that the sediments with highest concentration of hydrocarbons will be associated with reservoirs containing the highest amount of oil. This is probably true for rocks with intermediate-range hydrocarbon contents, but it may not be true for rocks with very high hydrocarbon contents. As previously mentioned, if the rocks are oil wet, they would tend to adsorb the oil instead of releasing it. Another system for identifying source rocks has been reported by BRAY and EVANS (1961). They pointed out that the normal paraffins of Recent sediments, which eventually become part of crude oil, have predominantly odd-numbered chain lengths. The ratio of the amounts of odd to even chain lengths of hydrocarbons is 3-5/1. The reason for this was first discovered by CHIBNALL and PIPER (1934). They found that insect and plant waxes contain primarily the odd-numbered paraffin chain lengths. As these waxes from living organisms find their way into the sediments they would maintain this ratio. In contrast, it was found by Bray and Evans that the normal paraffins in crude oil contain practically equal quantities of odd- and evenhumbered chain lengths of hydrocarbons. The ancient sediments that might be considered as possible sources of the crude oils contained normal paraffins that have a greater preference for the odd chain lengths than the crude oil accumulations. This is generally less pronounced for the hydrocarbons in Recent sediments. These results are summarized in Table x. Bray and Evans reasoned that the initial difference in odd and even chain lengths of paraffins in living organisms and in Recent sediments was gradually reduced as the hydrocarbons that were generated in the sediments were added to the original hydrocarbons from the living organisms. Generated hydrocarbons would have equal amounts of odd
244
J. M. HUNT
TABLE X RATIO OF ODD- TO EVEN-NUMBERED I2-PARAFFINS IN SEDIMENTS AND CRUDE OILS
Source
Ratio of odd- to even-numbered n-parafins chain length
Recent sediments ancient sediments crude oils
2.5-5.5 0.9-2.4 0.9-1.2
and even chain lengths. Consequently, if enough of these were formed in comparison with the amount originally present, they would tend to obscure the odd chainlength preference observed in hydrocarbons from Recent sediments. Bray and Evans concluded that a sediment could be considered a source rock if it generated enough hydrocarbons to reduce the odd-even carbon ratio to 1.20 or less.'This is about the maximum value observed in crude oils. By this technique, both the Canyon Limestone of Texas and the Heath Limestone of Montana could be defined as source rocks because their odd-even ratios averaged 1 .O and 1.1, respectively. Of course, any of these source-rock techniques require examination of several samples within a formation, because a formation may not be uniform in its capability of generating hydrocarbons. KHALIFEH and LOUIS(1961) developed an oxidation method for determining source rocks. Briefly, their method consists of measuring the reducing power of the insoluble organic matter in the rock by adding a strong oxidizing agent such as potassium permanganate. The ratio of reducing power to total organic carbon is then plotted against the weight percent carbon remaining after oxidation. This indicates the state of reduction at various stages in the oxidation process. Khalifeh and Louis obtained three types of curves: (1) A rising curve, indicating that the more resistant organic matter consumes more oxygen and, therefore, is more reduced. This is characteristic of a good source rock. (2) A descending curve, indicating that the more resistant organic material consumes very little oxygen, that is, it has already been oxidized to some extent. This is characteristic of a poor source rock, or more continental-type organic matter. (3) In some instances, a straight line is obtained indicating that the organic matter is similar to that found in Recent muds, that is, it is in a state .of evolution, or still in the process of being reduced. By this technique, the LaLuna Limestone of Venezuela appears to be a good source rock and the Kimmeridgien limestone of France appears to have not yet generated any oil. VEBERand GORSKAYA (1963) studied the chemical composition of dispersed
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
245
bitumens as a means of recognizing source rocks. They cited the bituminous limestones of Carboniferous age in the Donets Basin as an example of carbonate source rock. They found that the dispersed bitumen in the limestones is a true petroleum, and, according to Veber, it was clearly indigenous. In one section of the Viscan Limestone, the asphalt found in a fracture was generally similar in composition to the dispersed bitumen in the limestone matrix. Any method for distinguishing migrating (allochthonous) hydrocarbons from native (autochthonous) hydrocarbons would be a method of recognizing source rocks. The presence of large quantities of migrating hydrocarbons would imply good source characteristics. USPENSKIY et al. (1958) first proposed that changes in the degree of bituminosity (percentage of hydrocarbons) in the total organic matter could be used to recognize traces of oil which migrated. The idea is that if oil is migrating, being redistributed within the mother rock, there will be sections of high concentrations of hydrocarbons which will stand out over and above the levels due to indigenous hydrocarbons. These would be considered migrated hydrocarbons. VASSOEVICH (1958) defined this more precisely by showing that the percentage of hydrocarbons in the total organic matter increased as the content of organic matter decreased. NERUCHEV (1962) demonstrated these concepts by logarithmically plotting the percent of soluble bitumens in total carbon against the total organic carbon content as shown in Fig.3. The line in this figure separates the anomalously high values of soluble bitumens from the background values. Points above this line represent migrated bitumens, whereas those below the line represent native bitumens. It can be seen that the percent of native bitumens increases with decreasing organic carbon. Vassoevich, who edited Neruchev’s book, pointed out that each different type of rock would have its autochthonous hydrocarbons on a different part of the diagram. The line in Fig.3 would shift with lithology. For example, carbonate rocks are known to have high native bitumen content in their organic matter, so that the line separating migrated bitumens would be higher than that for clays. Unfortunately, Neruchev does not state just how he decides where to draw the line. Neruchev also distinguished native and migrated bitumens by plotting frequency distribution curves of the bitumen content of samples from individual formations. Anomalous values believed to be caused by migrating bitumens stand out very clearly on these graphs. Generally the native bitumens represent more than 75 % of the total. This is also evident in Fig.3. At the end of his book, Neruchev presented equations for calculating the quantities of native and migrated oils in a sediment. The calculations are based on the idea that when a source rock gives up oil, there is a reduction in the contents of carbon and hydrogen and a proportionate increase in the contents of oxygen, nitrogen and sulfur in the organic matter of the rock. Also, there is a decrease in the amounts of oily fraction and hydrocarbons in the rock. According to Neruchev, by determining the amounts of carbon, hydrogen, oxygen, nitrogen
246
J. M. HUNT
I
Mlgrated bitumens
i
.iT 50-
i
l
10
11
51
tumens
I
0
5
0
0 OO0
0.5
1
i I
I
I
0.1
0.1
0.5
Total organic carbon
(weight percent)
Fig.3. Relationship between the total organic carbon content and the ratio of soluble bitumens in 1962.) total carbon. (After NERUCHEV,
and sulfur in various fractions of the organic matter, one can calculate the quantity of oil that has migrated from oil-generating deposits and thereby estimate the amount of total undiscovered reserves in the basin under study. Although he recognized the difficulty in estimating the amount of oil lost due to the lack of reservoir cover, he still felt that this technique could be used in oil exploration.
CONCLUSIONS
Table XI attempts to summarize the various concepts relating to source rocks. It is recognized in any comparison of lithologies, such as carbonates and clays, that the entire spectrum of conditions may be present in both groups. The statements made are designed to highlight the more significant differences rather than describing a typical carbonate or shale source rock. Carbonate deposition in open shelf areas occurs in shallow, well-aerated waters. The slow rate of deposition allows adequate time for destruction of the fleshy material of marine organisms, leaving the organic matter, which is largely
247
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
proteinaceous, in the shells. Somewhat greater quantities of organic matter would be preserved in the less common evaporite basins. Clay particles, in contrast, come from the continents with adsorbed humic and lignitic organic matter, and are deposited in the deeper, rapidly subsiding parts of the basin. More organic matter is preserved due to the rapid deposition, but there is also more mineral matter. Thus, the percentage of organic matter in the sediment is about the same for clays and carbonates. Carbonates lose their water in the first few feet of burial and undergo early lithification and recrystalliTABLE XI COMPARISON OF CARBONATES AND SHALES AS SOURCE ROCKS OF PETROLEUM
environment of deposition: rate of deposition: source of organic matter: type of organic matter: compaction and lithification: process of hydrocarbon generation from organic matter: probable time of hydrocarbon generation: probable time of HC migration: probable mechanism of HC migration: proximity of reservoir porosity to source:
effectiveness of reservoir traps:
Limestones and dolomites
Clay shales
shallow, aerated on open shelf but reducing in evaporite basins slow primarily marine proteinaceous, some humic early loss of water, rapid lithification and recrystallization thermal
deep, often reducing rapid primarily terrestrial humic and lignitic slow and continuous loss of water catalytic and thermal
late
early and continuous
late, after lithification and fracturing of the rock and development of solution permeability in solution or as globules moving along fractures and solution paths very near; oolites and reefs; fracture complexes; frequently porosity is developed in or close to the source (solution and dolomitization) good, due to frequent proximity of impermeable anhydrite covers
early during major movement of fluids in solution with the expelled fluid variable; many thick source beds have no interbedded porous rocks
average, considerable amount of oil is lost through sands, silts and continental sediments
248
J. M. HUNT
zation. Clay sediments have a slow and continuous loss of water from 80 % porosity a t the surface to about 8 % at a depth of 10,000 ft. (HEDBERG,1936). Experimental laboratory results obtained at the Petroleum Engineering Department of the University of Southern California show that the remaining moisture content (percent dry basis), at an overburden pressure of 10,000 lb./sq.inch varies from 6-32 %, depending on the type of clay (G. V. Chilingar, personal communication, 1965). Due to the catalytic effect of clays, even in the presence of water, hydrocarbons can be generated quite early in this process and migrate within the first 500 ft. of sediment. Many of these hydrocarbons will be lost because of the lack of adequate rock cover; therefore, it is important that suitable reservoirs and traps form early enough to catch the hydrocarbons while the major fluid movement is still going on in the basin. At depths beyond 5,000 ft. hydrocarbons are probably still being generated, but, due to the great decrease in permeability .and the minor amount of fluid movement, the hydrocarbons would have difficulty inmigrating out of the shales. In carbonates, on the other hand, the early cementation and recrystallization to form a lithified rock would be accompanied by hydrolysis and solution of much of the organic matter and probably some of the initially deposited hydrocarbons. Later in its history, as the carbonate rock became buried deeper, hydrocarbons would be generated thermally from the remaining organic matter and would migrate along the solution or fracture zones. The solution zones could be formed by infiltrating meteoric waters, or by fluids moving up from the deeper parts of the basin. One advantage of carbonate source beds over shales is the frequent close proximity of porous reservoir beds. Studies of the hydrocarbon contents of source beds generally show them to be most effectively drained in the presence of interbedded porous sediments. In carbonates the source and reservoir rocks are frequently in juxtaposition. Reservoir porosity (oolite, solution and dolomite porosity) may be scattered capriciouslj throughout a carbonate rock, whereas in a shale bed the associated sand development is more clearly delineated. Many thick shale sections contain vast amounts of hydrocarbons which could have made oil pools had there been interbedded porous zones. Carbonates deposited in evaporite basins also have the advantage of impermeable anhydrite covers which retain the oil much better than do shales in typical sand-shale sequences.
ACKNOWLEDGEMENTS
The author is indebted to Dr. K. 0. Emery, Dr. F. Manheim and Dr.'E. T. Degens for reviewing the manuscript, and to Mrs. T. Perras for typing it. This work was partially supported by the National Science Foundation Grant No.1599 and Contract Nonr-2196(00) with the Office of Naval Research.
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
249
REFERENCES
.
ARABIAN-AMERICAN OIL COMPANY STAFF,1959. Abqaiq-Ghawar oil field, Saudi Arabia. Bull. Am. Assoc. Petrol. Geologists, 43: 434-454. BAKER,D. R., 1962. Organic geochemistry of Cherokee Group in southeastern Kansas and northeastern Oklahoma. Bull. Am. Assoc. Petrol. Geologists, 46: 1621-1 642. BAKER, .E. G., 1962. Distribution of hydrocarbons in petroleum. Bull. Am. Assoc. Petrol. Geologists, 46: 76-84. BAKER, N. E. and HANSON, F. R. S.; 1952. Geological conditions of oil occurrence in the Middle East fields. Bull. Am. Assoc. Petrol. Geologists, 36: 1885-1901. BALLIE, A. D., 1955. Devonian System of the Williston Basin. Bull. Am. Assoc. Petrol. Geologists, 39: 575429. BASS,N. W., 1963. Composition of crude oils in northwestern Colorado and northeastern Utah suggests local sources. Bull. Am. Assoc. Petrol. Geologists, 47: 2039-2064. J. G., B R O ~ N B., L. and HEPNER, L. S., 1963. Isolation and identification of isopreBENDORAITIS, noids in petroleum. World Petrol. Congr., Proc., 6th, Frankfurt, 1963, V(15). BERGMANN, W., 1949. Comparative biochemical studies on the lipids of marine invertebrates with special reference to the sterols. J. Marine Res. (Sears Found. Marine Res.), 8: 137-176. (Editor), Organic Geochemistry. B E R ~ ~ M AW., N N1963. , Geochemistry of lipids. In: I. A. BREGER Pergamon, Oxford, pp.503-535. BITTERLI, P., 1963. Aspects of the genesis of bituminous rock sequences. Geol. Mijnbouw, 42: 183-201. BLUMER, M. and OMAN,G. S., 1965. “Zamene”, isomeric Ci9 monoolefins from marine zooplankton, fishes, and mammals. Science, 148: 370-371. BLUMER, M. and THOMAS, D. W., 1965. Phytadienes in zooplankton. Science, 147: 111-1149. M., D. W., 1964. Pristane in the marine envirsnment. B~MER , MULLIN,M. M. and THOMAS, Helgolaender Wiss. Meeresuntersuch., 10: 187-201. BODUNOV-SKVORTSOV, E. I., 1958. Results of geochemical investigations in the southern part of eastern Siberia. Geol. Nefti, 2(1B): 51-56. BRAY,E. E. and EVANS, E. D., 1961. Distribution of n-paraffins as a clue to recognition of source beds. Geochim. Cosmochim. Actu, 22: 2-15. BROD,I. O., 1959. Diagnostic indications of the processes of formation of bitumens, petroleum and gas. Novosti Neft. Tekhn., Geol., 1959(9): 246-254. A. C. and PIPER,S. H., 1934. Metabolism of plant and animal waxes. Biochem. J., CHIBNALL, 28: 2009-2019. CHAYKOVSKAYA, E. V., 1960. The question of carbonate oil source beds in the Turukhansk and Noril’sk districts. Izv. Vysshikh Uchebn. Zavedenii, Neft i Gaz, 3: 19-25. DUNNINGTON, H. V., 1958. Generation, migration, accumulation and dissipation of oil in northern Iraq. In: L. G. WEEKS(Editor), Habitat of Oil. Am. Assoc. Petrol. Geologists, Tulsa, Okla., pp.1194-1251. DUNTON,M. L. and HUNT,J. M., 1962. Distribution of low molecular weight hydrocarbons in Recenfand ancient sediments. Bull. Am. Assoc. Petrol. Geologists, 46: 2246-2248. EMERY, K. 0. and HOGGAN,D., 1958. Gases in marine sediments. Bull. Am. Assoc. Petrol. Geologists, 42: 2 174-2 188. ERDMAN, J. G., MARLETT,E. M. and HANSON, W. E., 1958. The Occurrence and distribution of low molecular weight aromatic hydrocarbons in Recent and ancient carbonaceous sediments. Am. Chem. Soc., Div. Petrol. Chem., Preprints, 3: 639-649. FORSMAN, J. P. and HUNT,J. M., 1958. Insoluble organic matter (kerogen) in sedimentary rocks of marine origin. In: L. G. WEEKS(Editor), Habitat of Oil. Am. Assoc. Petrol. Geologists, Tulsa, Okla., pp.747-778. FROST, A. V., 1945. The role of clay in the formation of petroleum in the earth’s crust. Progr. Chem., 14: 501-509. GEHMAN JR, H. M., 1962. Organic matter in limestones. Geochim. Cosmochim. Acta, 26: 885-897. GERARDE, H. W. and GERARDE, D. F., 1961. The ubiquitous hydrocarbons. Assoc. Food Drug Officials U.S.,Quart. Bull., 25-26:l. GINSBURG, R. N., 1957. Early diagenesis and lithification of shallow-water carbonate sediments in
250
J . M. HUNT
south Florida. In: R. J. LE BLANCand J. G. BREEDING (Editors), Regional Aspects of Carbonate Deposition-Soc. Palaeontologists Mineralogists, Spec. Publ., 5 , pp.80-100. GORSKAYA, A. I., 1950. Investigations of the organic matter of Recent sediments. In: Symposium “Recent Analogs of Petroliferaus Facies”. Gostoptekhizdat, Moscow. HEDBERG, H. D., 1936. Gravitational compaction of clays and shales. Am. J. Sci., 31(184): 241287.
HOBSON, G. D., 1954. Some Fundamentals of Petroleum Geology. Oxford Univ. Press, London, 164 pp. HOLLMANN, R., 1962. Uber Subsolution und die “Knollenkalke” des Calcare Ammonitico Rorso Superiore im Monte Baldo (Malm; Norditalien). Neues Jahrb. Geol. Paliiontol., Monatsh., 4: 163-179.
HUNT,J. M., 1961. Distribution of hydrocarbons in sedimentary rocks. Geochim. Cosmochim. Acta, 22: 3 7 4 9 . HUNT,J. M., 1962. Geochemical data on organic matter in sediments. In: Intern. Sci. Congr. Geochem., Microbiol. Petrol. Chem., 3rd, Budapest, 1962, Rept., I : 393412. HUNT,J. M. and JAMIESON, G. W., 1956. Oil and organic matter in source rocks of petroleum. Bull. Am. Assoc. Petrol. Geologists, 40: 477488. JURG,J. W. and EISMA,E., 1964. Petroleum hydrocarbons: generation from fatty acid. Science, 1444(3625): 1451-1452.
KHALIFEH, Y . et LOUIS,M., 1961. Etude de la matiere organique dans les roches skdimentaires. Geochim. Cosmochim. Acta, 22: 50-57. G. M. and RODRIGUEZ-ERASO, G., 1956. Habitat of some oil. Bull. Am. Assoc. Petrol. KNEBEL, Geologists, 40: 547-560. KREJCI-GRAF, K., 1963. Origin of oil. Geophys. Prospecting, 1 1 : 244-275. LINDBLOOM, G. P. and LUPTON,M. D., 1961. Microbiological aspects of organic geochemistry. Develop. lnd. Microbiol., 2: 9-22. MAIR,B. J. and MARTINEZ-PICO, J. L., 1962. Compostion of the trinuclear aromatic portion of the heavy gas-oil and light lubricating distillate. Proc. Am. Petrol. Inst. Sect. I , 42: 173. MCAULIFFE, C., 1964. Solubility in water of paraffin, cycloparaffin, olefin, acetylene, cyclo-olefin, and aromatic hydrocarbons. In preparation. MEINSCHEIN, W. G., 1961. Significance of hydrocarbons in sediments and petroleum. Geochim. Cosmochim. Acta, 22: 58-64. MILLER, J. B., EDWARDS, K. L., WOLCOTT, P. P., ANISGARD, H. W., MARTIN, R. and ANDEREGG, H., 1958. Habitat of oil in the Macaraibo Basin, Venezuela. In: L. G. WEEKS(Editor), Habitat of’ Oil. Am. Assoc. Petrol. Geologists, Tulsa, Okla., pp.601-640. NERUCHEV. S. G., 1962. Oilgenerating Suites and the Migration of Oil. Goskhimhizdat, Leningrad. OAKWOOD, T. S.,SHRIVER, D. S., FALL,H. H., MCALEER, W. J. and WUNZ,P. R., 1952. Optically active substances in petroleum. J. Ind. Eng. Chem., 44: 2568. OWEN,E. W., 1964. Petroleum in carbonate rocks. Bull. Am. Assoc.Petro1. Geologists, 48: 17271730.
PHILIPPI,G. T., 1956. Identification of oilsource beds by chemical means. Intern. Geol. Congr., ZOth, Mexico, 1956, Rept., pp.25-38. PRATT,W. E., 1942. Oil in the Earth. Univ. of Kansas Press, Lawrence, Kansas, 105 pp. RONOV,A. B., 1958. Organic carbon in sedimentary rocks. Geochemistry, 5 : 510-536. SILVERMAN, S. R., 1962. Carbon isotope geochemistry of petroleum and other natural organic materials. In: Intern. Sci. Congr. Geochem., Microbiol. Petrol. Chem., 3rd, Budapest, 1962, Rept., I : 328-341. SMITHJR., P. V., 1954. Studies on origin of petroleum: occurrence of hydrocarbons in Recent sediments. Bull. Am. Assoc. Petrol. Geologists, 38: 377404. SOKOLOV, V. A., 1957. Possibilities of formation and migration of oil in young sedimentary deposits. In: Proc. Lvov Conf, 1957. Gostoptekhizdat, Moscow, pp.59-63. TREIBS, A., 1934. Chlorophyll and hemin derivate in bitumens, rocks, oil, waxes and asphalts. Ann. Chem., 510: 42-62. USPENSKIY, V. A. and CHERNYSHEVA, A. S., 1951. Material composition of organic material from the Lower Silurian limestones in the region of the town of Chudovo. Tr. Vses. Nauchn. Issled. Geologorazvcd. Neft. Inst., 57.
THE ORIGIN OF PETROLEUM IN CARBONATE ROCKS
25 1
USPENSKIY, V. A., CHERNYSHEVA, A. S. and MANDRYKINA, Yu. A., 1949. About dispersed form of hydrocarbon Occurrence in different sedimentary rocks. Izv. Akad. Nauk S.S.S.R., Ser. Geol., 5 : 83. F. B., CHERNYSHEVA, A. S. and SENNIKOVA, V. N., 1958. On the USPENSKIY, V. A., INDENBOM, development of a genetic classification of dispersed organic matter. In: N. B. VASSOEVICH (Editor), Questions of Formation of Petroleum (Symposium)-Tr. Vses. Nauchn. Issled. Geologorazved. Neft. Inst., 128: 22 1-3 14. N. B., 1955. The Origin of Petroleum (Symposium). Gostoptekhizdat, Leningrad. VASSOEVICH, N. B., 1958. Formation of oil in terrigenous deposits (especially the ChokrakVASSOEVICH, Karagansk deposits of the Tersk anterior basin). In: N. B. VASSOEVICH(Editor), Questions of Formation of Petroleum (Symposium)-Tr. Vses. Nauchn. Issled. Geologorazved. Neft. Inst., 128: 9-220. VEBER,V. V. and GORSKAYA, A. I., 1963. Bitumen formation in carbonate facies of sediments. Sov. Geol., 8: 51-63. N. M., 1958. Gaseous hydrocarbons in Recent sediments. Geol. VEBER,V. V. and TURKELTAUB, Nefti, 2: 3944, English translation in Petrol. Geol., 2: 737-742. WEEKS,L.G. (Editor), 1958. Habitat of Oil. Am. Assoc. Petrol. Geologists, Tulsa, Okla., 1384 pp. (Editor), WEEKS,L. G., 1961. Origin, migration and occurrence of petroleum. In: G. R. MOODY Petroleum Exploration Handbook, p.24. WEISS,A., 1963. Organic derivates of mica-type layer silicates. Angew. Chem. Intern. Ed. Engl., 2: 143. J . M., 1959. Compaction of sediments. Bull. Am. Assoc. Petrol. Geologists, 43: 273-310. WELLER, E. C., 1945. A. P. I. Research Project 43B. Proc. Am. Petrol. Inst., Sect. IV, 25: WHITMORE, 100-101. ZOBELL,C. E., 1959. Introduction to marine microbiology. In: C. D. OPPENHEIMER (Editor), Marine Microbiology-New Zealand Oceanog. Inst., Mem., 3: 1-23.
Chapter 8
TECHNIQUES OF EXAMINING AND ANALYZING CARBONATE SKELETONS, MINERALS, AND ROCKS K. H.
WOLF^,
A. J . EASTON AND
s. WARNE
Department of Geology, The Australian National University, Canberra, A.C.T. (Australia) British Museum, London (Great Britain) Newcastle University, Newcastle, N.S. W . (Australia)
SUMMARY
The increasing emphasis on detailed study of the petrology of carbonate rocks has led to the adoption of a multitude of techniques that are described in a series of widely scattered publications. A selection of these techniques, of proven value in specific studies, has been brought together in this chapter in the hope that they will contribute to carbonate studies in general. In many cases, refinements and an increase in reliability of a particular technique will rest on a simultaneous use of associated methods and modifications to suit specific cases. The interpretation of the analytical results must be based on sound genetic concepts, which in some instances also require new approaches as discussed in other chapters in this book. INTRODUCTION
The impetus given to carbonate sediment research in the past few years has led to the application of numerous techniques, some old and others rather new. They range from simple quick field tests to highly specialized, time-consuming, and elaborate instrument-requiring approaches. The existence of a large variety of techniques necessitates a rather superficial treatment of a number of them in this chapter. In some cases only a short discussion and a few pertinent references are given, but for the more important procedures details of both methods and results are outlined. In no case, however, is it possible to treat the methods adequately enough to make the reader independent of the original publications. Fig.1 gives a general scheme that includes most of the usual methods employed in carbonate investigations. Owing to limitations of space there can be no complete coverage of the literature, and some omissions of pertinent references are unavoidable. Much credit is due to the various research workers from whose publications much of the information has been extracted. Present address: Department of Geology, Oregon State University, Corvallis, Ore. (U.S.A.).
254
K . H. WOLF, A. J. EASTON AND S. WARNE
Fig.1. Flow chart of examining carbonate sediments. (Modified after SHORT, 1962, by permission of Am. Assoc. Petrol. Geologists, Tulsa, Okla.)
FIELD STUDIES OF CARBONATE SEDIMENTS
In most geological studies, field work and collecting of samples form the basis for more precise investigations in the laboratory. Therefore, the importance of obtaining as exact and detailed information as circumstances permit during field work, or on the well site, cannot be too overemphasized. In large-scale regional reconnaissance work one usually is not concerned with the precise petrographic make-up of sediments. Just as it has become routine to divide terrigenous sediments into arkose, greywacke, and so forth, an attempt should be made to give as detailed a description of carbonate rocks as the particular conditions allow. The carbonates will reveal many textures, and structures when etched with dilute (1 :lo) HCl acid and then wetted with water and examined with a hand lens. At least the grain size and the presence of dolomite and terrigenous impurities can be determined. In addition, the rock can be described as calcilutite (= micrite), calcisiltite, calcarenite, calcirudite, dololutite, dolarenite
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
255
or dolorudite; or where crystalline, as microsparite, sparite or dolosparite (see CHILINGAR et al., 1966, for an outline in describing carbonates both descriptively and genetically). For fine sediments, thin-section studies are absolutely necessary to check field interpretations. In the coarser rocks the percentage of grains, matrix, and sparite cement is also determinable by hand lens and many of the fossil types can be recognized. In particular, if a binocular microscope is available, e.g., on the well site or in the base camp, descriptive classification of the specimens is possible. This facilitates the collecting of samples for detailed thin-section examination that may permit a precise genetic classification. For example, calcareous rocks thought to be lithographic or micritic limestones, and described as unfossiliferous and massive when examined with a binocular microscope, have been shown in thin-section studies to be composed of blue-green algal filaments, cells, etc. (WOLF,1963a, 1965a; CHILINGAR et al., 1967). Some of the Algae are useful in dating such limestones (JOHNSON, 1964). Thus, in the case of apparently unfossiliferous, massive micritic limestones thin-section studies are most pertinent for a precise paleontological and petrographic interpretation. If paleontological studies are to be made predominantly on one particular phylum, e.g., corals, brachiopods, stromatoporoids or Bryozoa, a quick check on the associated “micrite” matrix components may assist paleoecological and environmental reconstructions. In addition, if the micrite proves to be of algal origin, it may be possible to observe symbiotic relations between the organisms. In strongly folded areas, it is useful to examine hand specimens for geopetal (top-and-bottom) criteria, which help in structural and stratigraphic reconstructions. For example, large brachiopods or primary reef cavities may be partly filled with sediments at the bottom and have an upper sparite growth, thus providing useful top-and-bottom criteria where limestones are vertical or overturned. For detailed studies on textures and structures, it is important to collect oriented hand specimens in order to understand the diagenesis and paleoenvironments; qnd it is necessary to investigate internal sediments, replacement patterns of hematite and dolomite, orientation of stromatactis, and so forth. In studying terrigenous rocks it is desirable to test for carbonate components. The carbonate may be present either as cement, or as carbonate detritals, or both. The importance of this distinction has already been stressed (WOLFand CONOLLY, 1965). The foregoing indicates that in spite of limitations, a field geologist should endeavor to collect all possible information from HC1-etched and water-wetted hand specimens to assist in stratigraphic work and to facilitate the selection of samples for subsequent laboratory studies. In remote areas where field camps may be set up for lengthy periods, it is advisable to have available binocular microscopes, diluted hydrochloric acid, staining material, and other equipment for more detailed examinations. More precise analyses may help in solving stratigraphic problems, in particular where a number of similar-looking carbonate formations outcrop.
256
K. H. WOLF, A. J. EASTON AND S. WARNE
ACID-ETCHING OF CARBONATE SEDIMENTS
Even in reconnaissance studies, it is desirable to carry out acid-etching as pointed out above. The acid-etched surface reveals textural and structural features and assists in the identification of dolomite. Etching is also used ( I ) as a preliminary step to staining; (2) in the preparation of peels; (3) for electron-microscope studies; ( 4 ) in the determination of percentages of mixtures of calcite and dolomite using, for example, comparative charts (TERRYand CHILINGAR, 1955); and (5) in extreme cases of etching, this procedure grades into the separation of insolubles by acid-digestion (to be described below). Etching is employed on relatively smooth broken surfaces, on polished surfaces, and on drilling chips. Depending on the information required, etching may be the only method applied, but for accurate studies it has to be supplemented by thin-section, staining, chemical, and other techniques. Carbonates composed of particles less than 0.5 mm in diameter require thin-section studies. In general, only calcitic, dolomitic and the non-carbonate materials are identified in routine work. The examination of well cuttings will not allow a very precise determination of percentages, and it is sufficient to subdivide them into four lithologic groups. The following procedure is recommended (Low, 1958). Use chips about 1 /4inch in diameter and 1/8 inch thick and immerse them in cold dilute HCI (I :7-10). Observe reactions under the microscope, in particular, if effervescence is slow (clean microscope afterwards to prevent damage by fumes). In straightforward cases the reaction will be approximately as follows. Limestone: violent effervescence; frothy audible reaction; specimen bobs about and tends to float to the surface. Dolomitic limestone: brisk, quiet effervescence; specimen skids about on the bottom of the container, rises slightly off bottom; there is a continuous flow of COZ beads through the acid. Calcitic dolomite: mild emission of COZ beads; specimen may vibrate, but tends to remain in one place. Dolomite: no effervescence; no immediate reaction; slow formation of COz beads on the surface of the rock; reaction slowly accelerates until a thin stream of fine beads rises to the surface. A number of factors will modify these reactions, e.g., presence of noncarbonate constituents such as clay, anhydrite, and bituminous material, and may drastically reduce the rate of effervescence of calcitic rocks. The rate of reaction is also dependent on the size of the chips, presence of adhering powdered carbonate material, film of water adhering to the surface or present in pores, degree of porosity and permeability, and other factors. With some experience, however, the modifying conditions are relatively easy to establish. Argillaceous limestone 0.r marl, for example, will effervesce fast at the beginning, but the reaction will progressively slow down. If a rock chip is crushed with the blunt end of a pair of tweezers
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
257
or a probe, a rejuvenation of the acid reaction will occur. On the other hand, dolomite will react very slowly at first and reaction will gradually become more vigorous especially if the acid is heated. Very porous and permeable dolomite cuttings may react with acid in a manner rather similar to limestone or argillaceous limestone because of the larger surface area available to the acid and the greater buoyancy of the dolomite. IRELAND (1950) mentioned the advantage of examining “curved surface sections” of carbonate chips digested in acid. Whenever polishing equipment is available, thecarbonatespecimens should be cut, polished and etched with dilute hydrochloric, acetic, or other acids, or mixtures thereof, before binocular-microscope examination is undertaken. (Note: aragonite may invert to calcite if too energetically ground.) The size of the samples depends, of course, upon the material available and the information desired. LAMAR (1950) and IVES(1955) used specimens approximately 6 inches long, 2 inches wide and 4-3 inch thick. WOLF(1963a) used slabs up to 10 x 10 inches and larger in the study of stromatactis, surge-channel and algal colonial structures. Large drilling chips can be polished quite simply (without a lap) on abrasive paper, for instance, before acid etching. After polishing and cleaning thoroughly to remove all abrasive, the specimen to be etched is placed in a dish with the polished surface up. Modelling clay is useful to hold the specimen in position. The polished surface should be horizontal, for an inclined surface may be channeled by rising streams of bubbles, and the grooves may be confused with genuine sedimentary features. The acids employed in etching carbonates as recommended by LAMAR (1950) are: 23 ml C.P. glacial acetic acid in 100 ml water, or 8 ml concentrated HCI acid in 100 ml water. The etching times required vary and experiments are necessary until the best result for the particular rock is obtained. Lamar suggested 20 min etching with acetic acid and 5 min in hydrochloric acid for limestones, but shorter times may suffice. Dolomites require a longer reaction period, mild heating of the acid, or both. In general, a slow reaction is necessary to prevent the destruction of delicate features. To initiate a very slow reaction, the specimen may be covered with about inch of water, and sufficient acid is then added to commence mild effervescence. A deep etch is required in some cases, and about 0.5 mm of rock may be dissolved from the flat surface. After the specimen has been etched for a period of time as determined by trial-and-error, the acid may be siphoned off using an eye-dropper, and replaced by water. In this fashion the specimen will not be moved and none of the minute surface features, e.g., adhering insoluble specks, will be destroyed or removed. If the specimen is taken from the dish, it is preferable to immerse it twice or three times into a beaker of water instead of washing it under a stream of water. Under no circumstance should the sample be brushed. The surfaces of limestones etched with acetic or citric acid are occasionally covered with a fine powder that precipitates when the specimen is dried. To remove
++
258
K. H. WOLF, A. J. EASTON AND S. WARNE
the absorbed salt, the specimen is soaked for a few hours in several changes of water, or is rinsed quickly in a very dilute hydrochloric acid. The results of acid etching differ somewhat for acetic and hydrochloric acid (see excellent photos by LAMAR,1950). The latter develops a so-called “acid polish” due to the absence of strong differential solution; exceptions, however, have been noted. Coarsely crystalline calcite often appears “glassy”, i.e., it has the sparry appearance. Internal fossil structures and differences in grain size of calcite particles are usually well shown, and textures and structures are distinctly brought out. Dolomite, clay, silt, sand, chert, and other insoluble or less soluble components project above the etched surface. Acetic acid reacts less uniformly with the carbonates and usually produces a rough surface in contrast to the smooth HC1-etched surface. The action of acetic acid is considerably influenced by porosity, incipient fractures, grain contacts, size and relative purity of calcite grains, and so forth. Due to local micro-variations, the core and concentric rings of oolites exhibit differential etching, and so do fossils and calcite grains, for example. Because of the rough surface produced, insoluble material is not readily seen on the etched surface, especially if the carbonate is coarse-grained or coarsely crystalline. In general, both acids should be used in order to determine which gives the best result, especially if peels are to be prepared from the polished and etched surfaces. One should try different acids at various concentrations applied for selected periods of time. In a combination treatment a mixture of acetic and hydrochloric acids produces etched surfaces combining the characteristic effects of the individual two acids, namely, a semi-polished and subdued differentially‘etched surface. Dolomite etching is done best with dilute HCl than with acetic acid because of greater speed of reaction. In the case of pure dolomite, there is little difference between HCI and acetic acid etching results. LAMAR (1950) mentioned that the etching results with citric acid are similar to those of acetic acid, as are those of organic and carbonic acids. Oxalic, sulfuric, and other acids that produce relatively insoluble reaction products with calcite or dolomite, are usually undesirable for etching. PERCIVAL et al. (1963) have described a technique for cleaning and etching the surface of carbonate rocks with hydrogenion exchange resin which reveals details in texture and fossil morphology. It cannot be emphasized too much that in many cases etched polished carbonate specimens are not sufficient to give genetic connotations to the components present. To distinguish between faecal, bahamite and algal pellets, between autochthonous and allochthonous micrite, and between genuine open-space sparite cement and recrystallization sparite, to name only a few examples, thin-section studies are a prerequisite.
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
259
STAINING OF CARBONATE ROCKS A N D MINERALS
Staining has been used in carbonate petrography for the following six purposes. ( I ) Identification of minerals (e.g., FRIEDMAN, 1959; GRASENICK and GEYMEYER, 1962; WARNE, 1962). (2) Identification of isomorphous series in combination with refractiveindex determinations (e.g., WALGER, 1961). (3) Textural and structural studies of recent and ancient calcareous fossils, 1913; SABINS, 1962; EVAMY, 1963). carbonate rocks and soils (e.g., HEEGER, (4) Petrogenetic investigations, e.g., diagenesis, paragenesis (e.g., SABINS, 1962; EVAMY,1963). (5) Percentage determination (visual estimates or with point-counter). (6) For illustration purposes, because stained grains are more distinct from surrounding non-stained material in photomicrographs (e.g., SABINS, 1962; EVAMY, 1963). The staining procedures are applicable to 'the study of thin-sections with removed cover-slides (as long as heating is not required), smoothly broken handspecimens, drilling chips, polished surfaces, and uncemented loose carbonate material in the field, on well site, and in the laboratory. Certain methods have advantages over others, and it is often left to the individual investigator to select a technique most suitable for his purposes. In general, little skill and only a few utensils are necessary to obtain satisfactory results. Table I (WOLF,1963b) gives a number of staining reagents, procedures of application, and results. The more pertinent references have been given which should be consulted for details on staining of carbonates. A number of staining methods have not been included in the table, e.g., techniques using malachite green (HENBEST, 1931; HEDBERG, 1963) and methyl red (RAMSDEN,1954). One of the tests for dolomite is based on the fact that this mineral usually contains some iron in contrast to the calcite. Inasmuch as most carbonate minerals can contain traces of iron, this test may not be a safe one to employ in precise work. EVAMY (1963) proposed a scheme which enables the discrimination between iron-free and iron-containing calcite and dolomite on a semi-quantitative basis (Table 11). Results of staining are most reliable in the case of mineralogic end-members. As indicated in Fig.5, however, a number of isomorphous (solid-solution) replacements are possible and caution is in order in the interpretation of staining results. LEITMEIER and FEIGL(1 934) and GOTO(196 I , p.6 14) observed that minerals from different localities react differently to staining probably because of varying degrees of purity. Results also change with the optical orientation of the crystals. The reactions, however, occur between certain limits and are still useful for gross identifications. One of the major limitations of staining is its application to granular and
TABLE I OUTLINE OF STAINING METHODS FOR CARBONATE MINERALS
(After WOLF,196313) Chemicals
Preparation and method
Results
FeC13, (NH4)zS
RODGERS (1940): use 1 part of FeC13.6HzO and 10 parts of water and immerse specimen not more than 1 min, then wash specimen gently and dip it into (NH4)zS. STRAKHOV (1957) stated: in a solution of 1 0 4 5 % of FeC13 moisten the carbonate specimen 1-2 min, or put a drop of the solution on the specimen. Wash specimen with distilled water and then treat it with a solution of (NH&S for a few seconds. Wash again with caution. FRIEDMAN (1959): use 2.5% of a FeCh solution (=2.5 g in 97.5 ml of water); apply to the specimen for a few seconds.
Calcite = brown-black. Aragonite = brown-black. Dolomite = nearly colorlesspale green.
Remarks
The dolomite grains when smaller than
0.01 mm become nearly black. Ankerite,
magnesite, breunnerite, and siderite when below 0.01 mm in size and slightly green (STRAKHOV, 1957). The disadvantage of this stain is Ankerite = nearly colorless-pale its tendency to spread over adjacent green. grains; and it oxidizes, turning brown, Magnesite = colorless. Breunnerite = greenish. cracks and crumbles. Also, the film is (STRAKHOV, 1957.) easily washed off. If limonitic material is present Brucite = pale green. (Somewhat darker than dolomite; LEMBERG, in the rock, it will be changed to black 1888.) FeS by the (NH4)zS and will make Siderite = colorless. carbonate estimation difficult. If other black materials, e.g., carbonaceous components and magnetite, are present as impurities the stained carbonate is difficult to estimate. (1 888), According to LEMBERG dolomite and calcite cannot be distinguished if they are very fine grained. .~
AIzCls hematoxyline HZOZ
FAIRBANKS (1925): use 0.24 g of haematoxyline, 1.6 g of AlzCk and 24 ml of water. This solution is boiled and then cooled. A small amount of HZOZis then added to oxidize the haematoxyline to hematein. Immerse
Calcite = violet or purple. Aragonite = violet or purple. Dolomite = colorless. Ankerite = colorless. Magnesite = colorless. Breunnerite = colorless.
LEMBERG (1888): use 4 parts of &CIs, 6 parts of logwood and 60 parts of water, and boil it under constant stirring for 20-30 min. The dark violet mixture is filtered and used as staining fluid. STRAKHOV (1957), using the above
carbonate specimen in solution.
Siderite = colorless. Brucite = colorless.
method, diluted the solution with 1,OOO2,000 ml of water. He boiled the carbonate specimen for 5-10 min. On the other hand, Lemberg did not dilute the solution and did not boil the specimen. Different logwood contain different amounts of haematoxyline and hematein, and the stains formed according to Lemberg’s method are not uniform. Hence, Fairbanks’ preparation method is preferable. Disadvantages: (I) solution is unstable, (2) stain contracts and spalls off, (3) stain rubs off easily, and (4) due to spalling it is not useful if carbonates are very small. ~~
ordinary photographic paper
(1931): use 2 parts of HCI, HENBEST 88 parts of water and 10 parts of K3 Fe(CN)e solution and immerse the specimen for 30-70 sec. Better effects are obtained by using more dilute HCI and treating the specimen longer. (1963) in the study of HEDBERG cores used the same solution, but treated the samples for 5-60 min depending on composition. WARNE(1962): use solution of equal parts of 2 % HCI and 2 % K3 Fe(CN)6. Heating may be required according to Warne in the case of siderite and dolomite. The former reacts rapidly, whereas it may take 5 min for the dolomite to stain.
Dolomite = blue-dark blue if Fez+ is present (it is colorless if it lacks Fe).
(1957), According to STRAKHOV the above solution is best applied with ordinary photographic paper. This
STRAKHOV’S (1957) results with photographic paper: calcite and dolomite gave no
Fe-dolomite = dark blue. Ankerite = dark blue. Siderite = dark blue. Calcite and magnesite stain if they contain Fez+.
The solution is unstable and gives off HCN (poisonous). For relation between Fe content and rate of reaction and intensity of (1913) and EVAMY stain see HEEGER (1963) (see below and Table 11). Certain clays also stain relatively easysometimes easier than the carbonates. Warne reported that ankerite and ferroan dolomite stain well in cold solutions, whereas dolomite generally and siderite always require heating. On using cold and hot reagents, this test seems useful for the differentiation of ankerite and Fe-dolomite from siderite and possibly dolomite. The intensity of blue is related to the amount of Fez+ present.
s2 ?-
5
E;
2: ?-
2
U ?-
2:
F*
e
m
m
E!
E
2P * 0
>
6z ?-
;;I
m
TABLE I (continued) Chemicals
Preparation and method
Results
Remarks
ordinary photographic Paper (continued)
paper is washed in hyposulphite causing it to turn dark. Then it is soaked in 1 % 1 :20 HCI for a few seconds to a minute. The paper is pressed against the carbonate specimen for 1-10 min. Then the paper is soaked in a solution of KaFe(CN)g followed by washing in water and drying.
color impression. Ankerite = blue. Breunnerite = deep blue. Siderite = deep blue.
KaFe(CN)a alizarin red S HCI
For results see Table 11. EVAMY (1963): use the staining solution in combination with alizarin red S as shown in Table 11. The reagents can be employed independently or the alizarin red S and K3Fe(CN)e can be combined in a single solution. The solution is then acidified by 0.2 % HCI.
EVAMY’S (1963) method permits a rough estimation of the amounts of Fe content in calcite and dolomite and the recognition of ankerite.
Calcite = red-orange-red-brown. (I 892): required are LEMLIERG neutralsolutionsof 10”/.AgN03and20% K ~ C r 0 4Put . drops of former solution Aragonite = spotted red or unstained (see remarks). on the specimen, heat it to 60-70°C (others boil it), and maintain it for Dolomite = nearly colorless. 2-5 min. Then wash the sample care. Ankerite = nearly colorless. fully and treat the specimen with Magnesite = nearly colorless. K2CI-04 solution for a few seconds. Breunnerite = nearly colorless. Wash again and let it dry. FRIEDMAN (1959): immerse the Siderite = colorless. According to Friedman: specimen for 2-3 min and use a Magnesite = brown. saturated K2CI-04 solution. THUGETT (1910) and STRAKHOVGypsum = brown. Dolomite = colorless. (1957) suggest a 0.1 % AgN03 solution. According to LEMBERG
The rate of staining of the less reactive carbonates, e.g., dolomite, depends on the grain size. STRAKHOV (1957) found that large grains of dolomite remain unstained, whereas those smaller than 0.01 mm become brown. Aragonite from different localities reacts differently according to ( I 892). If the AgN03 LEMBERC solution is too strong (greater than 273, the reaction between aragonite and the solution is too vigorous and no stain adheres to the surface; hence, apparent unstained appearance. The reaction of aragonite is 1,800 times that of calcite
( I9 10). If a very weak AgN03 (I .7 % = ( 1892) and THUGETT strontianite, magnesite and dolomite react only very slowly (see aragonite stains red, witherite column to the left). slightly red, and strontianite remains unaffected.
0.1
~~
MnS04.7HzO AgzS04 NaOH (Feigl’s solution)
diphenylcarbazide alcohol NaOH or KOH
~
N)solution is used for 1 sec,
~~
In 100 ml of water dissolve 11.8 g of MnS04.7HzO. Add to the solution solid AgzSO4 and boil. After cooling, filter the insoluble material. Then add 1-2 drops of dilute NaOH solution, and filter off the precipitate after 1-2 h. Keep reagent in a brown bottle. Put specimen into solution (powder, for 3-5 min; sections, for 30-50 min). Instead of placing the specimen into the solution, it can be dabbed gently with some material soaked in the Feigl’s solution.
Aragonite = grey. Strontianite = grey. Witherite = grey. Calcite, dolomite, magnesite, ankerite, siderite, smithsonite, and cerussite need much longer time than the above three to stain.
A test-tube or some other container is filled with about 15 cm3 of alcohol and 1-2 g of diphenylcarbazide is dissolved by heating. Then add 3-5 mg of NaOH or KOH (25 %). Add the grain of carbonate to be examined and boil for 2-3 min. The solution is poured out and the specimen boiled with some water. The water is changed until it remains uncolored. FErGL (1958) recommended to place drops of hot solution on a spot plate before adding the rock. After 5 min the solution is pipetted out and
Magnesite = lilac. Breunnerite = rose. (STRAKHOV, 1957) = colorless (FEEL, 1958). Siderite = dark grey (STRAKHOV, 1957). All other carbonates remain unstained according to STRAKHOV (1957). According to FElGL (1958), magnesite becomes red-violet. When Mg is in dolomite
(THUGETT,1910). (I 892) gives staining LEMBERG procedures for some non-carbonate minerals as well.
RP 3
I
.
______
LEITMEIER and FEIGL (1934) give a table showing the reactions of numerous carbonates in time. Sequence of reaction is as follows: (I) aragonite, strontianite, witherite, (2) smithsonite; (3) cerussite, ankerite, (4) dolomite; (5) calcite; (6) siderite; (7)crystalline magnesite; and (8) pure gel magnesite. Minerals from different localities often react somewhat differently but always within certain limits.
z >
2
>
2 U
> z > r $ E r A
B
5> XI
< > c1
STRAKHOV (1 957) recommended a procedure for the preparation of stained thin-sections. Note slight apparent discrepancy between the results of STRAKHOV (1957) and F E E L (1958). The latter stated that magnesite can be distinguished from both dolomite and breunnerite by this test. The reaction does not take place “when the magnesium carbonate is in the form of dolomite which is usually regarded as a double carbonate CaMg(CO3). .regarded as the complex CaMg(C0a)z. The magnesium
E
0
z >
3
.
h)
Q\
w
h,
TABLE 1 (continued)
m
P
Chemicals
Preparation and method
Results
Remarks
diphenylcarbazide alcohol NaOH or KOH (continued)
replaced by hot water. The washing continues until the water remains clear.
combination (or in breunnerite). no color results. The Mg can then be detected by taking a fresh sample and igniting it on platinum. The resulting sample can be stained as described above. (See test using magneson.)
is thus a constituent of a complex anion, and therefore has lost its normal reactivity. . .” Breunnerite is isomorphous with dolomite and also gives no reaction for magnesium. If dolomite and breunnerite are ignited, the dolomitic linking is destroyed and Mg can be detected with diphenylcarbazide, in the resulting mixture of oxides. (See magneson test.)
The powder of the carbonate is boiled for 2-3 min. in a solution of 5 % of Cu(N03)~.Thenthe solution is decanted and the specimen washed in 1940; STRAKHOV, water (RODGERS,
Calcite = bright green. Aragonite = bright green. Dolomite = unstained or pale green. Ankerite = pale green. Magnesite = pale blue. Breunnerite = unstained. Siderite = unstained.
Large dolomite grains remain unstained, whereas those smaller than 0.01 mm become pale green. See recommended procedure using C~(N03)zPIUS NH40H.
The specimen is put for 5-6 h in a solution of 5 % Cu(N03)~.The solution is removed and the specimen treated for a few seconds with a solution of concentrated ammonia. (1 940) and RODGERS FRIEDMAN (1959) recommended a molar solution of Cu(NO3)z (= 188 of Cu(N03)z ,225 g of Cu(N03)z. 3Hz0 or 332 g of Cu(N0&.6HzO
Calcite = blue-green. Aragonite = blue-green. According to Ross (1935): Mn-rich calcite = unstained. Siderite = unstained. Ankerite = unstained. Rhodochrosite = unstained. Pure calcite = blue-green.
1Y57.)
to 1,OOO g of water) into which the carbonate specimen is immersed for 2.5-6 hours depending on intensity of stain desired, and then treated with NHIOH (without washing and before drying) for a few seconds. (See also Ross, 1935; and STRAKHOV, 1957.) The carbonate specimen is boiled for 5 4 min in a concentrated solution Of cO(N03)z. FRIEDMAN (1959): use 2 cm3 of 0.1 N Co(N03)~solution to which 0.2 g of the sample is added, boil and filter. LEITMEIER and FEIGL (1934, following Meigen): use a 5-10% Co(N03)~solution and boil specimen 1-5 min depending on grain size.
~~
eosin KOH
Calcite = unstained, or lilacrose, or faint blue. Aragonite = dark violet. Dolomite, ankerite, magnesite, breunnerite, and siderite remain unstained.
.~
~
Fill test tube half full with alcohol (about 15 ml) and dissolve 1-2 g of eosin by heating. Add about 3 mg of 25 % KOH. The carbonate specimen is placed into the solution and boiled for about 2 min. Then the solution is decanted and the specimen 1957). washed with water (STRAKHOV, (Eosin = red tetrabromofluorescein)
Coarsely crystalline calcite remains unstained. Microcrystalline calcite becomes lilac-rose. After boiling for 10 min, the calcite becomes light blue. LEITMEIER and FEEL(1934) stated that calcite stains grey, green, yellow, or blue, but never violet when boiled for some time. Some contradictions have been 1959.) reported. (See FRIEDMAN, Boiling time may be critical. Not useful for staining thinsections as boiling is required. (1934) LEITMEIER and FEIGL reported spreading of stain over adjacent grains.
Calcite = unstained. Aragonite = unstained. Dolomite = unstained. Ankerite = unstained. Magnesite = faint rose. Breunnerite = pale rose. Siderite = faint rose.+
TABLE I (continued) Chemicals
Preparation and method
Results
Remarks
magneson NaOH and HCI
WARNE(1962): prepare the reagent by using 0.5 g of magneson (= paranitrobenzene-azoresorcinal) added to 100 ml of 0.25 N (= 1 %) NaOH. The HCl-etched and washed specimen is covered with equal amounts of reagent and 30 % cold NaOH solution. MANN(1955): suggested to drop some dilute HCl on the specimen; and when all effervescence has ceased, a drop of the alkaline magneson solhtion is introduced into the earlier drop. (See a h 0 STRAKHOV, 1957.)
Magnesite = blue. Smithsonite = unstained or shows faint tint to blue after 5 min. Calcite may stain if immersed too long. Dolomite = unstained Breunnerite = unstained. According to MANN(1959, MgO is present if the drop turns blue in about 30 sec.
The stain is unstable and disappears rapidly. Dolomite and breunnerite do not stain in the alkaline solution because the Mg forms a complex ion and is not available for the reaction with the dye (FEIGL,1958, p.465). If dolomite is ignited in a platinum crucible, the dolomite linking is destroyed and MgO is formed. MgO reacts with the dye. If HCI acid is put on the dolomite prior to adding the alkaline magneson solution, the Mg is precipitated and allows the magneson to become attached to it and color it. This latter test does not show whether the Mg comes from a dolomite or magnesite, for example.
methylviolet (violet writing ink)
Two possible procedures are proposed by STRAKHOV(1957): (I) To an ordinary violet writing ink (methylviolet) add a small. amount of HCl, causing a change to green color. If one drop of that solution is put on calcite or dolomite, the acid is more rapidly neutralized by calcite than dolomite. (2) Oxidize the methylviolet with 5 % HCl until an intense blue color is obtained. Soak the carbonate specimen in the solution (or put a
m
(1) The spot on the calcite
5
turns immediately violet; on the dolomite the spot remains green for some time.
(2) Calcite = violet. Aragonite = violet. Dolomite = unstained or pale violet.
0 2:
The dolomite crystals less than 0.01 mm in size become pale violet.
layer of the solution on the specimen) and leave it there for 1.5-2 min. Apply carefully a blotting paper. alizarin red S 2 % HCI
alizarin red S 30% NaOH
alizarin red S 5 % NaOH
z 2
Dissolve 0.1 g of alizarin red S in 100 cm3 0.2 % cold HCl(0.2 % HCl = 2 cm3 of concentrated HCI plus 998 ml of water). The specimen to be tested is first etched in 8-10 % HCI (see WARNE,1962, p.34) and then covered with the cold alizarin red S solution and allowed to react for about 2-5 mill. SCHWARTZ (1929), FEIGL (1958), FRIEDMAN (1959), and WARNE(1962).
Calcite, aragonite, high-Mg calcite, and witherite = deep red. Ankerite, strontianite, Fe-dolomite, and cerussite = purple. Anhydrite, siderite, dolomite, rhodochrosite, magnesite, gypsum, and smithsonite = no color.
Use equal volumes of alizarin red S and 30 % NaOH solutions (30 % NaOH = 30 g of NaOH plus 70 ml of water). Add specimens to be tested and boil for 5 min. Alizarin red S solution is prepared by dissolving 0.2 g of the dye in 25 ml methanol, by heating if 1959). Replenish necessary (FRIEDMAN, any methanol lost by evaporation.
Calcite = no stain. High-Mg calcite = purple. Dolomite = purple. Magnesite = purple. Gypsum = purple. Anhydrite = no stain. Witherite = no stain. Siderite = dark brown-black. Rhodochrosite = purple. Smithsonite = purple. Aokerite = dark purple. Cerussite = dark red-brown. Strontianite = no stain.
Use equal volumes of alizarin red S and 5 % NaOH solution and boil therein for about 5 min. Etch specimen first in 10% HCI. (See WARNE, 1962, p.34; and FRIEDMAN, 1959.)
Dolomite = unstained or faint color. Rhodochrosite = unstained or faint color. Magnesite = purple. Gypsum = purple. Smithsonite = purple.
2; WARNE(1962) reported that no staining occurred when reagent was applied for 5 min. Prolonged staining produced slightly purplish surface on the dolomite. According to SCHWARTZ (1929) staining is successful with carbonates with grain-size of 0.5-1.5 mm. Below this size distinction becomes difficult due to spreading of the stain.
5 2
+ z U > z
EE
8 vl
F;
3
Etch the specimen first in 10% HCl (WARNE,1962, p.34). HENBEST (1931): use KOH instead of NaOH (1 part KOH to 119 parts of water in which the maximum amount of alizarin red S is dissolved). Alizarin red S at 26°C has a solubility of 7.6 % in water.
> w
*
0
>
ti2 2
vl
-
s
h,
TABLE I (continued) Preparaiion and method
Results
titan yellow 30% NaOH
Boil carbonate s w i m e n to be tested in solution of titan yellow and 30% NaOH (FRIEDMAN, 1959).
Calcite = unstained. Aragonite = unstained. Anhydrite = unstained. High-Mg calcite = orange-red. Dolomite = orange-red. Gypsum = orange-red. Magnesite = orangered.
titan yellow 5 % NaOH
Boil specimen in solution of titan yellow and 5 % NaOH (FRIEDMAN,
High-Mg calcite = orange-red. Gypsum = orange-red. Magnesite = orangered. Dolomite = unstained.
1959).
..
Hams’ hematoxylin
rhodizonic acid
---
Remarks
High-Mg calcite studied by Friedman
(1959) was very fine grained. Degree of
coloration of the high-Mg calcite apparently depends on the amount of Mg present (FRIEDMAN, 1959).
- -- -
Harris’ hematoxylin can be purchased commercially or can be. prepared as described by FRIEDMAN (1959). Solution is made up of 50 ml commercia1 grade Harris’hematoxylin and 3 ml 10% HCI. 3-10 min are required to stain specimen.
Calcite = purple. High-Mg calcite = purple. Aragonite = purple. Magnesite = no stain. Gypsum = no stain. Anhydrite = no stain or faintly orange. Dolomite = no stain.
The more frequently the solution i s used, the quicker the stain takes effect. A fresh solution will often require 9-10 min to stain, whereas a frequently used solution may need only 3 min or less (FRIEDMAN, 1959).
Dissolve 2 g of disodium rhodizonate in 100 ml of distilled water. The specimen to be tested is etched in dilute HCI and washed several times in distilled water. The specimen is then submerged in the reagent for 5 min (FEIGL,1958; WARNE,1962).
Witherite = orange-red. Calcite = no stain.
T h e spot test proposed (FEIGL,1958,
x T
x sl
Chemicals
3
&!.
? 2 m
% p.220) utilizing sodium rhodizonatc, can detcct strontium in very small quantities.
4
5
v1
I > a
z
benzidine
Dissolve 2 g of pure benzidine Rhodochrosite = blue stain in 100 ml of water which contains (almost immediately). 1 ml of 10 N HCI. The HC1-etched Dolomite = not stained. specimen is washed several times, after which the specimen is immersed in a dilute solution (1-3 %) of NaOH for about 1.5 min. Then it is covered with cold benzidine solution (WARNE.1962).
See FEEL(1958, pp. 175 and 416) for spot test using benzidine. (The production of benzidine has been discontinued by some companies because of the cancer risks involved in the preparation of the pure material.)
rn
x
$
2
$z
5U
270
K. H. WOLF, A. J. EASTON AND S. WARNE
crystalline carbonates of which the individual particles are larger than about 0.01 mm. STRAKHOV (1957) found that below this grain size some staining procedures lead to results that differ from those obtained on using coarser material. Some staining methods depend on the rate of solution of the carbonate in acid, e.g., difference between aragonite and calcite (FRIEDMAN, 1959), and between calcite and dolomite. In the latter case, very finely powdered dolomite forms C02 rapidly and, therefore, may be confused with calcite (HEEGER, 1913). A few of the staining reagents spread readily over neighboring particles and make identification and percentage determinations difficult. Hence, it may be necessary to modify the manner of application of the reagents. For example, gentle dabbing of the specimen with a cloth soaked in the reagent, or pressing the specimen against a reagent-wetted blotting paper may give satisfactory results. A similar approach may be required to prevent staining fluids from penetrating into openings in the case of porous carbonate rocks. As has been illustrated by FRIEDMAN (1 959) and WARNE (1962), a few of the staining techniques listed in Table I can be used to identify most of the major carbonate minerals by a progressive elimination scheme shown in Fig.2 and 3. The other methods are given for those who wish to experiment with different techniques and for the purpose of double-checking a mineral identification. Further research on the applicability of staining for semi-quantitative determinations of isomorphous minerals and minor element-containing carbonate minerals, possibly in combination with spot tests, may improve and expand the methods available at present.
I
Alizorln red S t3OXNoOH boll
ANHYORITE
HIGH-Mg CALCITE
SIDERITE
[ree=,
CALCITE
WITTHERITE
DOLOMITE RHOOOCHROSITE
ANKERITE STRONTNNITE CERUSSITE
MAGNESITE WITHSONITE
or
GYPSUM
Fig.2. Staining scheme for the identification of carbonate minerals employing alizarin red S; (After WARNE,1962b, by permission of the Journal of Sedimentary Petrology.) I = or faint stain.
m x
TABLE I1 STAINING METHOD OF CALCITE, DOLQMITE AND ANKERITE, CONSIDERING Fe-CONTENT
(After EVAMY, 1963) _
Staining reagents
Calcite
Compositions are given in weight percent. Critical solution strengths are underlined.
Fez+
__
Fez+
Fez+
Dolomite
Fez+
Fez+ MT+ 10
b (*Is%) b(55%) a (52%) a (52%) a (f2%)
b,c (f2%) b,c ( M %) a,b (*2%) a,b ( 5 2 % ) -
b,c ( 4 2 % ) b,c (52%) b (32%) b (&2%) -
a = spectrophotometricanalysis; b= E.D.T.A. titration; c = gravimetric analysis.
293
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
TABLE V TRACE ELEMENTS ANALYSIS~
U
Na K Li Rb Sr
cs Sb As Ba Be B Br CI
+ + + + + ++ +
U2
Th2 Se Ag Sn Ti W V Zn Zr Ra2
-
co
+ + +
cu F
Ga Ge Au Pb Mn Hg Mo Ni
-
1
Cd Cr
_____
-
-
U
b
+
P
+ +-
-
P
+ + + ++ +-
-
P P
-
-
-
+ + + + +-
+
P P
+ + +
C
+ + + P + + + + + + P + P + + P + -
d -
+ +-
+ + +-
+ + + + +-
Neutron activarion. With the exception of the halogens, Li and Be, most other elements, including the rare earths, can be determined by this technique. Although this method has the advantage of sensitivity, the equipment involved is costly. This is the only technique available for certain elements at the concentrations in which they occur. (a) Flame-photometry. Although a number of elements have been indicated in the table as being determinable by flame-photometry, with the exception of the alkalies Na and K, complex separations are often necessary to remove major elements that would otherwise interfere in the determination. Separation of organic complexes containing the element to be determined increases the sensitivity, and allows the determination of elements which otherwise would not be practical. (b) Spectrometry (copper electrodes). Extra sensitivity is obtained by the use of copper-spark emission techniques. The great advantage of spectrographic equipment is that a large range of elements may be determined at the same time. (c) Spectrophotornetry. This technique enables the determination of a large number of elements, although the time involved is sometimes greater than that required by other techniques. Ionexchange separations have assisted in the removal of interfering elements. (d) X-ray spectrograph (X-ray fluorescence). Similar to spectrographic techniques, the same sample may be used for the determination of a number of elements, particularly those with high atomic numbers. The sample may also be stored for future reference.
+
= determination possible; - = determination impossible; P = Explanation of symbols: determination by this technique preferred. Neutron activation is the technique preferred for these elements.
TABLE VI CHEMICAL ANALYSIS OF SOME RECENT AND ANCIENT CARBONATES ROCKS
(Determined by A. J. EASTON)
I
Sample No.
Moisture (%) Loss on ignition (%) Acid insoluble residue (%) CaO MgO Fez03 FeO MnO Ti02 Crz03 Pzos AhOs Na K Sr S (total) c1 Total (%)
0.58 44.80 0.17 50.60 2.54 0.01 1 0.005 0.003 lo%), e.g., in siderite, the iron may interfere by the mechanism of air-reoxidation of the iron-tiron complex. In this case the iron present in the aliquot may be held as the colorless ferrous E.D.T.A. complex which does not undergo air-reoxidation (EASTON and GREENLAND,1963). Measure the absorbance of the solution against water in a 1-cm cell using a spectrophotometer with the wave-length set at 430 mp. Compare the absorbance of the sample solution with a standard curve prepared by treating aliquots of a standard titanium solution in a similar manner. Preparation of standard curve (Fig.10). A standard titanium solution may be prepared by fusing 0.02 g of pure titanium dioxide with 2 g of potassium bisulphate in a platinum crucible. After allowing the crucible to cool, the fusion cake is dissolved from the platinum crucible with 3% v/v sulphuric acid by heating until a clear solution is obtained. The volume is then adjusted to 1 1 with 1 % v/v sulphuric acid; thus 1 ml will contain 0.02 mg of titanium as TiO2. Place at least six aliquots of the standard titanium solution ranging from 0.02-0.1 mg in 100-ml beakers, and buffer solutions as before. After measuring the absorbances, construct a curve relating absorbance against milligrams of titanium in each beaker. Determination of chromium The chromium (0.02-0.1 mg Crz03) in an aliquot is oxidized by the addition of ammonium persulphate and silver nitrate (catalyst). The iron is separated by neutralizing the solution with solid sodium carbonate, the precipitate is centrifuged off and discarded. The solution is acidified with sulphuric acid and an excess of 1 ml is added. Then 10 ml of 0.1 % w/v diphenylcarbazide solution (in acetone) is added forming a pink complex with the chromate (VANDER WALTand VANDER MERWE, 1938).The absorbance is measured at a wave-length of 540mp andcompared
303
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
0.6
0
Ti02 (mg)
Fig. 10. Hypothetical “standard curve” of absorbanceversus Ti02 content used in spectrophotometry. Wave length 430 mp; volume as given; 1 cm cell. Fig.11. Hypothetical “standard curve”ofabsorbance versus Crz03 content used in spectrophotometry. Wave length 540 mp; volume 50 ml; 1 cm cell.
with a standard chromium curve prepared from potassium dichromate (Fig.11). Note: Manganese present as permanganate interferes with the reaction between chromium and diphenylcarbazide (A. J. EASTON, 1964); and if present, it may be reduced by the addition of E.D.T.A. solution before the chromium-diphenylcarbazide complex is formed. A 0.1 % w/v E.D.T.A. solution is added dropwise into the flask until the permanganate color is almost discharged in the sample solution. If no permanganate color is present in the solution, this addition is omitted. Determination of phosphorus The phosphorus in the aliquot combines with the vanadomolybdate reagent to form yellow vanadomolybdic phosphoric acid (KITSONand MELLON,1944). Inasmuch as the reagent solution itself has an absorbance at 430 mp, the absorbance of the sample solution is measured against a reagent blank so that the difference in absorbance is due only to the complex formed by the phosphorus. This difference in absorbance is then compared with a standard phosphorus curve. An aliquot containing 0.01-0.3 mg of phosphorus as Pz05 is placed in a 50-ml volumetric flask and the vohme adjusted with water to approximately 15 ml. Where the phosphorus content is low, a 15-ml aliquot may be taken initially. Add 10 ml of vanadomolybdate solution. Prepare the reagent solution by dissolving 1.25 g of ammonium metavanadate (NH4V03) in 400 ml of cool 50% v/v nitric acid. Separately dissolve 50 g of ammonium molybdate in 400 ml of water and filter off any solid particles that may remain. Add the ammonium molybdate solution to the ammonium metavanadate solution and adjust the volume to 1 1. Adjust the volume to 50 ml with water and shake well to ensure complete mixing. Measure the absorbance of the solution after 5 min against the reagent
[!L
304
K. H. WOLF, A. J. EASTON AND
S. WARNE
0.15
a 0.05
a
0
0.15
0.3
P205 (mg)
Fig.12. Hypothetical “standard curve” of absorbanceversus PZOScontent used in spectrophotometry. Wave length 430 my; volume 50 ml; 1 cm cell.
blank in a 1-cm cell, using a spectrophotometer with the wave-length set at 430 mp. The reagent blank is prepared by adding 10 ml of vanadomolybdate solution to a 50-ml volumetric flask and then adjusting the volume with water. Compare the absorbance of the sample solution with a standard curve prepared by treating aliquots of a standard phosphorus solution in a similar manner. Preparation of standard curve (Fig.12). A standard phosphorus solution may be prepared by dissolving a quantity of a standard phosphate rock (e.g., National Bureau of Standards phosphate rock 56) by adding 25 ml of 50% v/v nitric acid to the weighed material in a 150-ml beaker. The beaker is covered with a watch glass and the contents allowed to digest for several hours on a steam bath until the material is dissolved. A suitable concentration of the standard solution is 0.02 mg of phosphorus as PzO5 per 1 ml. Dilute solutions of phosphorus should not be stored in polyethylene bottles due to absorption of phosphorus by the walls of the container. Note: If the phosphorus content of the sample is sufficiently high so that it will not be completely precipitated with the Rz03 group, then it will remain in the filtrate. In this case it will be necessary to add a small quantity of aluminum chloride to the acidified filtrate, and then precipitate the aluminum phosphate by the addition of ammonium hydroxide as in the normal precipitation of the Rz03 group described above. The precipitate is washed free of calcium and magnesium salts by 1 % w/v ammonium nitrate solution, and then dissolved in warm 3 % v/v sulphuric acid. The solution is next transferred to a volumetric flask (e.g., 50-ml). An aliquot is then taken and the phosphorus determined with vanadomolybdate solution as given above. Determination of alurninum For the determination of aluminum two main methods are available: ( I ) gravimetric, and (2) titration with E.D.T.A. (BISQUE and LEMISH,1959). Other methods
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
305
include a spectrophotometric measurement after extraction of aluminum oxinate (RILEYand WILLIAMS, 1959b). If a scheme of analysis has been used that requires the separation of the Rz03 group (i.e., Fig.7 left), then the aluminum may be determined by subtraction of the other constituents from the total Rs03 content. This method is usually referred to as “by difference”. An alternative method is that of titration with E.D.T.A., which may be used when the scheme shown in Fig.7 (right) has been applied to the sample. Gravimetric method “by difference”. When using this method certain considerations must be taken into account. First, the oxides are present in the ignited Rz03 group in the following form: Fez03, TiOs, Mns03, Cr203, phosphorus chiefly as AlP04, and excess aluminum as A1203. MnsOa is calculated from manganese determined as MnO by multiplying by a factor of 1.11; whereas P04. by multiplying the PzO5 found by a factor of 1.35. The second consideration is that where aluminum is a minor constituent of the RzO3 group, the magnitude of the errors involved in the determination of the other constituents may impair the accuracy of the determination of aluminum. Where this is the case and iron is the major constituent, e.g., siderite-bearing samples, the iron may be separated by an ion-exchange technique which leaves the iron retained on the column whereas the other constituents are elutriated (EASTON and LOVERING, 1963). The advantage of this separation is that the aluminum is then obtained as a relatively major constituent, and, therefore, is determined with increased accuracy. Determination of calcium Two wet chemical methods are available for the determination of calcium: (I) gravimetric precipitation as calcium oxalate followed by ignition to calcium oxide; and (2) titration with E.D.T.A. The latter method has the advantage of being a rapid procedure. A third useful physicochemical method for the determination of the MgO and CaO has been described by CHILINGAR and TERRY(1954). The sample is heated in a micro-crucible at a constant rate in a current of COz and the temperature -weight relationship is determined; from this the MgO and CaO contents can be calculated. Calcium gravimetric method (GROVES,1951). Add sufficient water to the filtrate obtained earlier from the Rz03 group precipitation (p.298) so that the volume is approximately 250 ml, contained in a 600-ml beaker, and heat to boiling after acidifying with a few drops of hydrochloric acid. While boiling add 10 ml of 5 % w/v ammonium oxalate solution and one or two drops of universal indicator. Add ammonium hydroxide dropwise until the indicator changes from red to blue;
306
K. H. WOLF, A. J. EASTON AND S. WARNE
continue boiling for 10-20 min. The presence of a boiling stick assists in the prevention of bumping. Set the beaker aside on a water bath for 1-2 h, and then allow to remain cold for 4-5 h to ensure complete precipitation of the calcium oxalate. Filter off the precipitate through a 540 Whatman filter paper and wash the precipitate with 1 % w/v ammonium oxalate solution three or four times. Dissolve the precipitate back into the original beaker with hydrochloric acid and wash the filter paper with hot water. Reprecipitate the calcium oxalate after adjusting the volume again to 250 ml and adding 5 ml of the ammonium oxalate, by the addition of ammonium hydroxide as before. (The second precipitation being made in a nearly salt-free solution avoids the coprecipitation of other ions, e.g., Mg.) After boiling for 10 min, the precipitate is again set aside as before. The precipitate is filtered through a 540 Whatman filter paper and washed with 1 % w/v ammonium oxalate solution. The precipitate is ignited in a weighed platinum crucible, initially at a low temperature and finally at 1,100"C. After cooling in a desiccator for 30 min, the calcium is weighed as the oxide. The ignition is repeated until a constant weight is obtained. Note: The precipitate also contains SrO; thus an adjustment is made after measurement of strontium by the flame photometry method. Calcium titration method (PATTONand REEDER,1956) Transfer the combined filtrate obtained earlier from the Rz03 group precipitation (p.298) to a volumetric flask, e.g., 250 ml, and adjust to volume with water. Shake well to ensure complete mixing. Place an aliquot containing approximately 25 mg of calcium as CaO in a 250-ml beaker. Add 10 ml of concentrated nitric acid and evaporate to dryness on a steam bath to remove the ammonium salts. Rinse down the sides of the beaker, add 2 ml of nitric acid, and evaporate again. Take up the residue with approximately 50 ml of water and transfer to a 250-ml conical flask. Add 10 ml of a 10% w/v sodium hydroxide solution (pH should be ~ 1 2 )and , a few milligrams of both sodium cyanide and hydroxylamine hydrochloride. Stopper the flask and set aside for 1 h. Any magnesium present will precipitate as magnesium hydroxide. After the period of standing, add a few milligrams of Patton and Reeders acid]. This reagent [2-hydroxy-1 (-2 hydroxy-4-sulpho-l-naphthylazo)-3-naphthoic reagent is usually diluted: 0.0375 g with 20 g of sodium chloride. Then titrate with 1 % w/v E.D.T.A. (disodium salt) until the indicator changes from red to a clear sky blue color. The E.D.T.A. solution is standardized against a standard calcium solution prepared from calcium oxide obtained by heating A.R. calcium carbonate to 1,OOO"C for 1 h and then cooling in a desiccator for 30 min. Dissolve 1 g of the freshly ignited CaO in 100 ml of 5 % v/v hydrochloric acid and dilute to 1 1 with
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
307
water; then each 1 ml will contain 1 mg of calcium as CaO. Use 25-ml portions of the standard calcium solution to standardize the E.D.T.A. solution. Determination of magnesium Two methods are available for the determination of magnesium: (I) gravimetric precipitation as magnesium pyrophosphatel, and (2) titration with E.D.T.A. Where magnesium carbonate is only a minor constituent, e.g., a fraction of 1 % as in some limestones, the titration method is preferred. Magnesium gravimetric method (GROVES, 1951). Adjust the volume of the two filtrates obtained earlier from the calcium precipitation (see the section on the calcium titration method) to approximately 800 ml in a 1-1 beaker. Make the solution just acid with a few drops of hydrochloric acid and add several drops of universal indicator. Add 10 ml 10% w/v ammonium phosphate solution and stir to mix. Add ammonium hydroxide dropwise stirring vigorously until the magnesium pyrophosphate precipitate just appears. Cease the addition of ammonium hydroxide and stir vigorously for several minutes. The slow precipitation ensures a coarse crystalline precipitate. Continue the addition of ammonium hydroxide until the indicator turns purple (pH 11), then add excess ammonium hydroxide, 5 ml for each 100 ml of solution, and set aside overnight. Filter through a 540 Whatman filter paper and wash the precipitate with 5 % v/v ammonium hydroxide solution three or four times. Dissolve the precipitate into the original beaker with 25% v/v hydrochloric acid, washing the filter paper well with 200-300 ml of water. Add 5 ml more of 10% w/v ammoniumphosphate solution and several drops of universal indicator. Reprecipitate as before after adjusting the volume to approximately 800 ml. Filter and wash the precipitate as before and ignite in a weighed platinum crucible. Care should be taken during the filtration of the magnesium pyrophosphate that the surface of the glass funnel above the filter paper remains dry. If this is not the case, the precipitate will tend to creep up the glass. This may be counteracted by washing particles down into the filter paper with ethyl alcohol. The precipitate should be ignited at a minimum temperature with free access of air to avoid reduction of the phosphate. Then the temperature should be raised slowly until it reaches approximately 1,OOO"C. The crucible is allowed to cool in a desiccator for 30 min before weighing. It is ignited again until a constant weight is obtained. Inasmuch as there is a possibility that manganese will not completely precipitate with the R203 group, the magnesium pyrophosphate precipitate is examined for manganese. Actually magnesium ammonium phosphate is the precipitate, and magnesium pyrophosphate is the result of ignition.
308
K. H. WOLF, A. J. EASTON AND S. WARNE
Examination of precipitate for manganese. The ignited precipitate is dissolved in 5 ml 15 % v/v sulphuric acid and the solution transferred to a volumetric flask (e.g., 50 ml). Either the whole solution or an aliquot is taken and the manganese is determined as permanganate by the procedure given under the analysis of the R2O3 group. The weight of this manganese is added to that previously found in the R203 group. The weight of manganese determined as MnO is converted to Mn2P207; on using a factor of 2 before deduction from the weight of the magnesium as MgzPz07; 0.3621 * MgzPz07 = MgO. Magnesium titration method (CHENGet al., 1952). Transfer the two filtrates from the RzO3 group precipitation to a volumetric flask (e.g., 250-ml) and adjust to volume with water. Shake well to ensure complete mixing. Place an aliquot containing approximately 25 mg of magnesium as MgO in a 250-ml beaker and acidify with hydrochloric acid. Then add 5 ml of 5 % w/v ammonium oxalate solution to precipitate the calcium present, and while the solution is gently boiling neutralize with ammonium hydroxide solution and add 2-3 ml in excess. After boiling for 10 min, allow the beaker to cool and stand for 2 h; then filter off the precipitated calcium oxalate through a 540 Whatman filter paper into a 250-ml conical flask. Test the filtrate for completeness of precipitation of the calcium by adding one or two drops of 5 % w/v ammonium oxalate to the solution. Upon warming, no turbidity should develop if the precipitation is complete. If a turbidity does develop, add 5 ml more of the ammonium oxalate solution and boil, allow to stand and filter as before. Heat the solution almost to boiling and add one or two drops of 10% w/v hydroxylamine hydrochloride solution to reduce any manganese present. Then add 10 ml of ammonium hydroxide buffer (to 60 g of NH4CI dissolved in 200 ml of water, add 570 ml of ammonium hydroxide and dilute to 1 I). Add 1-2 ml of solochrome black (eriochrome black) solution (0.2 g of reagent dissolved in 50 ml of ethyl alcohol) and titrate with 1 % w/v E.D.T.A. (disodiumsalt) solution until the indicator changes from red to clear sky blue color. The E.D.T.A. solution is standardized against a standard magnesium solution prepared from magnesium oxide. The latter is obtained by heating A.R. magnesium carbonate to 1,OOO"C for 1 h and then cooling in a desiccator for 30 min. Dissolve 1 g of the freshly ignited MgO in 5 ml of hydrochloric acid and dilute to 1 1 with water; then each 1 ml will contain 1 mg of magnesium as MgO. Use 25-ml portions of the standard magnesium solution to standardize the E.D.T.A. solution.
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
309
Determination of ferrous iron Apparatus. Fit a 250-ml conical flask with a tight-fitting rubber stopper in which three holes have been bored. To two holes fit a piece of glass tubing bent at right angles. One is for the entry of an oxygen-free inert gas, e.g., COz, Nz. To the second attach a Bunsen valve to allow exit of the gas. Place a thistle funnel with a stopcock capable of holding 20 ml of acid in the third hole. Method. The sample is dissolved in hydrochloric acid in the absence of oxygen so that the ferrous iron present in the sample remains in the reduced state. 2,2'dipyridyl solution is added and forms a sufficiently strong complex with the ferrous iron to avoid oxidation during the removal of the insoluble material by filtration. Weigh out a quantity of the sample which will contain 0.05-0.5 mg of iron calculated from the total iron determination (see above). If the iron content is high, the quantity to be taken should be such that a ten-fold dilution after solution of the sample will bring it to within this range. Transfer the weighed material to the conical flask and add 20 ml of water; then swirl the contents carefully to wet the sample. Connect the inert gas supply and allow it to pass through the flask for 5-10 min to expel the air. Add 10 ml of 10% v/v hydrochloric acid to the thistle funnel, depress the Bunsen valve and slowly add the acid to the contents of the flask. After the vigorous reaction has finished, release the Bunsen valve to its normal position and warm on a water bath to 50-60°C for 30 min to complete the reaction. After this period, allow the flask to cool to room temperature either naturally or by cooling in a trough of cold water. Disconnect the gas supply and immediately add 10 ml of 0.2% w/v 2,2'dipyridyl solution (prepared in 1.5 % v/v hydrochloric acid). Filter the solution through a previously water-washed 541 Whatman filter paper into a 100-ml volumetric flask, washing the sides of the conical flask with small portions of water. Wash the residue several times with small portions of water. If a maximum of 0.5 mg of iron has been calculated to be present, add 25 ml of sodium acetate buffer (272 g CHsCOONa.3HzO per liter) and adjust the volume to 100 ml with water. If 5.0 mg of iron has been calculated to be present in the solution, adjust the volume to 100 ml, mix well and pipette a 10-ml aliquot of this solution into another 100-ml volumetric flask. To this flask add 5 ml of 0.2 % w/v 2,2'-dipyridyl solution and 25 ml of sodium acetate buffer, and adjust to 100 ml with water. Measure the absorbance of the solution against water in a 1-cm cell using a spectrophotometer with the wave-length set at 522 mp.Compare the absorbance of the sample solution with a standard curve (Fig.l3), which may be calculated from the curve prepared for the determination of total iron (see above). The ferric iron is calculated by converting the FeO value to Fez03 and sub-
3 10
K . H. WOLF, A. J. EASTON AND S. WARNE
0.6
“c 01
0.3 0 n u)
a
0
Fig. 13. Hypothetical “standard curve” of absorbanceversus FeO content used in spectrophotometry. Wave length 522 mp; volume 100 ml; I cm cell.
tracting this from the total iron taken as Fez03; the difference is the amount of ferric iron, i.e., Fez03 (0.9 * Fez03 = FeO). Determination of sodium, potassium and strontium
The determination of these elements by flame-photometry requires the measurement of the radiation emitted by these elements from a solution excited by a flame (DEAN,1960). The sample solution is drawn up in a finely divided state into a flame, and the resulting radiation compared with that given by standard solutions under the same conditions. A number of combinations of flame condition and instrument are available. The details given here are for a Beckman flame-photometric attachment, but the procedures for measurement of background and elimination of interferences are generally applicable. Interferences. The main interfering ions in the determination of sodium and potassium are the members of the RzO3 group, i.e., Fe, Al, and the elements Ca and Mg. The interfering elements emit their own characteristic radiation which interferes with that of the alkalies, e.g., Fe and Ca. The other type of interference is a depression ofthe radiation, and this is exhibited by A1 and Mg. It is for this reason that the Rz03 group and calcium are separated before the measurement of the alkalies in the flame. In the case of strontium only, the Rz03 group is removed (DIAMOND, 1955); the precipitation of calcium would also precipitate the strontium as oxalate. The interference caused by magnesium is eliminated by the use of standard addition technique, provided the background radiation is first deducted. Background. When small quantities ( < O . 1 %) of sodium and potassium (also 1964), a large slit width is restrontium) are measured (EASTONand LOVERING, quired which will allow extraneous radiation also to be measured. This radiation,
31 1
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
72 5
768 Potassium
825
Fig.14. Curve constructed to determine both the background and peak heights of each sample and standard; examplified here by potassium. The relevant wave lengths for each element are given in Table VII. In all subsequent measurements, used for obtaining either an approximate value (Fig.15) or for the standard addition technique (Fig.l6), the background is deducted leaving only the peak height to be plotted. (Wave lengths in mp.)
which is not associated with the radiation from the elements to be measured, is known as background (Fig.14). In the case of potassium it is necessary to take readings of the background at both 725 and 825 mp and calculate graphically the background at 768 mp. The wave lengths for the measurement of the peak and background radiation are given in Table VII.
Preparation of the sample solution for sodium and potassium. Weigh 0.5 g of the sample into a 250-ml beaker, add 25 ml of water followed by 10 ml of 50% v/v hydrochloric acid, and place the beaker on a water bath for 30 min to allow complete solution of the carbonate portion of the sample. Wash the cover glass into the beaker and add 1 g of A.R. oxalic acid; heat gently at first to dissolve the sample and then heat almost to boiling. Pass ammonia vapor through the solution until the solution is neutral to Universal indicator paper. This will precipitate the RzO3 group components as hydroxides and the calcium as calcium oxalate. The passage of compressed air through a wash bottle containing ammonium hydroxide (s.g. = 0.88) is a convenient method of obtaining the ammonia vapor for the neutralization. After neutralizing the solution, stand the beaker on a steam bath for 10 min to complete precipitation. TABLE VII WAVE LENGTHS FOR THE MEASUREMENT OF RADIATION
peak background
(mp)
Na
K
Sr
588 580 or 600
768 125 and 825
46 1 466
312
K. H. WOLF, A. J. EASTON AND S. WARNE
The precipitated hydroxides and calcium oxalate are centrifuged off using clean glass tubes. The supernatant liquid is collected in a 50-ml volumetric flask, I .5 ml of hydrochloric acid is added and the solution is allowed to cool before being adjusted to volume with water. This solution is set aside for measurement of the amounts of sodium and potassium. A blank is prepared by using the same quantity of reagents as above. Preparation of sample solutionfor strontium. Weigh 0.5 g of the sample into a 250-ml beaker, add 25 ml of water followed by 10 ml of 50% v/v hydrochloric acid, and place the beaker on a water bath for 30 min to allow complete solution of the carbonate portion of the sample. Wash the cover glass into the beaker. Pass ammonia vapor through the solution until the solution is neutral to universal indicator paper. After neutralizing the solution, stand the beaker on a steam bath for 10 min to complete precipitation. The precipitated hydroxides are centrifuged off using clean glass tubes. The supernatant liquid is collected in a 50-ml volumetric flask, 1.5 ml of hydrochloric acid is added and the solution is allowed to cool before being adjusted to volume with water. This solution is set aside for the measurement of strontium. Preparation of standard solutions. Weigh 2.54 g of dried A.R. sodium chloride (for Na standard), 1.91 g of dried A.R. potassium chloride (for K standard), and 1.685 g of dried A.R. strontium carbonate (for Sr standard) into three separate 100-ml beakers. Dissolve the material in 20-50 ml of water (add a minimum of HCI for the SrC03) and transfer the solutions to three 1-1flasks; then make up to volume with 1 % v/v hydrochloric acid. The concentration of Na, K and Sr in these solutions is 1,OOO p.p.m. These solutions are then diluted with 1 % v/v hydrochloric acid to the required range of concentrations: this will usually be 1-10 and 10-100 p.p.m; (0.1-1.0 for the blank).
I
Concentration (ppm. Na, K or S r )
Fig.15. Curve constructed from four standards such that the radiation given by the sample lies within the range covered by that of the standards. The background has been deducted in each case prior to plotting. The approximate concentration (in p.p.m.) of the element in the solution is obtained by reference to the horizontal axis. This approximate value is used as a guide to the strength of the standard solutions required when using the “standard addition” technique (see Fig. 16).
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
313
Measurement of approximate value. First, an approximate value is obtained by direct comparison with standards both above and below the transmission given by the sample. Turn the wave-length dial to the peak transmission for the element and adjust the slit width so that the highest standard selected gives a high transmission reading, e.g., 80-90 %. Now place the standards and sample solution alternately in the flame, repeating the operation until constant readings are obtained and the sample solution has been bracketed by standards. Record these readings and repeat the operation for the same solutions, with the dial turned to the background wave-lengths to obtain readings on any background present. Subtract the background from the readings and use the peak heights to obtain an approximate value (Fig.15). Deduct the appropriate blanks. Measurement by standard addition. Having obtained an approximate value of the content by the procedure given above, place 5-ml aliquots of the sample solution in four 25-ml beakers. To the first beaker add 5 ml of water and to the other three add 5 ml of standard solutions, so that the first addition is equal in parts per million to the previously found approximate value. The others are of higher concentrations. Swirl to mix the four solutions and then place them in succession in the flame with the wave-length dial turned to the peak wave-length. Record the transmission. Repeat the operation with the wave-length dial turned to the background wavelength to obtain readings of any background present. If a background is present, subtract this from the former readings. These results are now plotted graphically as shown in Fig.16, and the line joining the points is projected back to the base line from which the concentration of the unknown sample solution is read. Determination of total sulphur (A. I. VOGEL,1951)
Weigh up to 25 g of the sample into a 400-ml beaker and add 100 ml of saturated bromine water; stir to ensure complete wetting of the sample. Add nitric acid dropwise until the sample is dissolved. A violent reaction should be avoided because loss of HzS will cause a low result. After solution of the sample, gently heat the solution to discharge the excess bromine. After the bulk of the bromine has been discharged, filter off any insoluble residue through a 541 Whatman filter paper. Wash the residue three or four times with hot water. Add 10 ml of hydrochloric acid to the filtrate and evaporate to dryness on a water bath to discharge the nitric acid. Take up the residue in 250 ml of hot water and heat to boiling. Remove the beaker from the heater and add 10 ml of hydrochloric acid to make the solution acid (0.5 N). Slowly add 10 ml of hot 5 % w/v barium chloride
314
Content
K. H. WOLF, A. J. EASTON AND S. WARNE
0 Addition (ppm. Na,K or Sr)
Fig.16. Curve constructed to determine the exact concentration by “standard addition”. Point I, indicating the lowest percentage of transmission, represents 5 ml of the unknown sample (whose concentration has been determined approximately) plus 5 ml of water. Point 2: 5 ml of the unknown sample plus 5 ml of a standard of about the same concentration as the approximate value of the unknown sample. Point 3: 5 ml of unknown sample plus 5 ml of a standard having 50% higher concentration than that used for point 2. Point 4, indicating the highest percentage of transmission, represents 5 ml of unknown sample plus 5 ml of a standard having 100% higher concentration than that used for point 2. In all cases the background has been deducted and the peak heights plotted. Point 0 indicates zero addition only and is not to be confused with “zero content” which lies farther to the left on the horizontal axis. p.p.m. x 50 = weight in micrograms of the element; weight of the element in grams x 100 divided by the weight of the sample gives the percentage.
solution, stirring continuously. Allow the beaker to stand on a water bath for 2 h, filter precipitate through a 540 Whatman filter paper, and wash with small portions of cold water. Continue the washings until the filtrate is free from chloride, as shown by allowing a few drops of the filtrate to collect in a test tube containing 1-2 ml of 1 % w/v silver-nitrate solution. Ignite the precipitate in a previously weighed platinum crucible, allowing free access of air to avoid reduction of the barium sulphate. Continue ignition until a constant weight is obtained. Calculate the sulphur content of the sample from the weight of the ignited BaS04: 0.13735 * Bas04 = S Determination of sukhur trioxide (NATIONAL BUREAUOF STANDARD METHODS, 1928). Weigh up to 25 g of the sample into a 400-mlbeaker and add dilute 50 % v/v hydrochloric acid until the sample is dissolved. Then add additional 10 ml of acid and evaporate the solution nearly to dryness. This will discharge any sulphide present in the sample, leaving sulphate ions in the residue. Increase the volume to 250 ml with hot water and filter off any insoluble residue through a 541 Whatman filter paper; wash the residue three or four times with hot water. Heat the solution to boiling. Precipitate the sulphate, filter and ignite the precipitate as described above for the determination of total sulphur.
315
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
Chlorine (A. I. VOGEL,1951)
The chloride ions present in the neutral sample solution are titrated with silvernitrate solution. In the presence of a slight excess of silver ions, a red coloration, (i.e., silver chromate) is formed indicating the end point of the titration. The surface of the sample should be cleaned with dilute 5 % v/v nitric acid. Weigh 2-5 g of the sample into a 250-ml beaker and add sufficient nitric acid under a cover glass to dissolve the sample. Warm until the reaction has ceased, then filter through a 541 Whatman filter paper. Evaporate the filtrate to dryness on a water bath and bake for 1 h to expel any excess nitric acid present. Dissolve the residue in 100 ml of water and transfer the solution to a 250-ml conical flask. Check by the use of Universal indicator paper that the solution is neutral and add a small excess of A.R. ammonium acetate in the solid form. Add 1 ml of 2.5% v/v potassium-chromate solution as indicator and titrate with silver nitrate solution (1.699 g AgN03/1). The end point is indicated by the formation of deep-red silver chromate. 1 ml of silver nitrate solution = 0.0003546 g CI.
DIFFERENTIAL THERMAL ANALYSIS
The use of differential thermal analysis (D.T.A.) equipment is now routine in petrological and mineralogical laboratories. This technique is widely used for carbonate minerals and rock studies. The latest equipment, once loaded with the test sample and switched on, will continuously record the endothermic and exothermic data as a thermogram at preset heating rate, sensitivity and furnace atmosphere conditions. Carbonate minerals considered here are classified in Table VIII. For reference, thermograms characteristic of these carbonates, obtained from specimens of known chemical composition, are given in Table IX. These were determined from material crushed to -150 mesh (B.S.S.), heated at lSoC/ min, while the furnace atmospheres other than air were maintained by a 2 I/min TABLE VIII CLASSIFICATION OF SOME CARBONATE MINERALS
Calcite group
Aragonite group
Dolomite group
siderite magnesite calcite
aragonite witherite strontianite
dolomite ankerite
316
K. H. WOLF, A. J. EASTON AND S. WARNE
TABLE IX CHEMICAL ANALYSIS OF SOME CARBONATE MINERALS'
Mineral
CaCO3 Mgc03 FeCO3 MnCO3 BaCO3 SrCO3 Bas04 SiOz
ankerite calcite dolomite magnesite siderite witherite strontianite
51.63 98.70 50.82
-
1.46 0.70 7.60
19.05
28.23 0.48 5.52 0.96 81.86
trace
39.33 99.40 9.50
-
-
1.09
trace 6.38
-
-
-
95.57
-
-
-
0.07
-
-
-
-
0.48
0.10
-
2.16 92.42
Fez03
1.61
-
-
4.33
-
-
-
-
Total
f %I
100.07 99.18 100.00 100.36 99.78 100.04 100.02
1 The D.T.A. and T.G.A. curves of the listed minerals are given in this chapter. These analyses were generously provided by the Western Australian Government Chemical Laboratories, the New South Wales Department of Mines, and the School of Applied Geology, University of New South Wales.
of a particular gas flow. This, together with the apparatus used, has been described elsewhere (WARNE,1964). BECK (1950), WEBBand HEYSTEK(1957) and SMYKATZ-KLOSS (1964) provided D.T.A. data on less common carbonates; whereas the marked influence on thermogram configuration of controllable variables, and specifically crystallinity, (1 962) and BAYLISS(1964). has been described respectively by BAYLISSand WARNE
Calcite group1 Siderite (FeCO3) The thermogram of siderite determined in air is characterized by a single endothermic peak Ed./ (sometimes preceded by a small exothermic peak: Ex.I), which is followed by two exothermic peaks Ex.2 and Ex.3 (Fig. 17, curve 13). The peak temperatures occur at approximately 520", 590", 675 " and 850°C. The conflicting published decomposition mechanisms of siderite were reviewed by WARNE(1961), from which it would appear that the decomposition mechanism described by KULPet al. (1951) is the most acceptable. It involves three reactions:
+
(I) FeCOa-tFeO COz? (2) 2Fe0 O+a-Fez03 y-Fez03 (3) y-Fez03-ta-Fez03
+
+
endothermic (Ed./) exothermic (Ex.2) exothermic (Ex..?)
For the D.T.A. of rhodochrosite (MnC03) and smithsonite (ZnCOa), see KissiNGER et al.
(1956) and WEBBand HEYSTEK (1957), respectively.
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
317
The small exothermic peak, Ex.1, has been attributed (PAPAILHAU, 1958) to the immediate oxidation of the FeO released during the initial slow decomposition of FeC03. After a small increase in temperature, however, the endothermic decomposition rate rapidly increases and becomes dominant (Ed.I). The major exothermic peak, Ex.2, is generally partially superimposed on the preceding endothermic peak, Ed.1, which consequently shows some size reduction. When determined in COz or inert gases, the thermogram is composed solely of the fully developed endothermic peak, Ed.1, caused by the reaction I given above (Fig.17, curve 12). In Nz and COz the thermograms are similar, except that the commencement of the reaction and its peak temperature occur at slightly higher temperatures in COe. The second reaction probably occurs because the end product is magnetite (Fe304) (cf. KISSINGER et al., 1956). The reaction rate must be slow and uniform as no additional recognizable peak is recorded: 3Fe0
+ COz+Fe304 + CO f
SCHWOB(1950) indicated that such a reaction was possible, and the slow oxidation of FeO, liberated by the D.T.A. of siderite in nitrogen, has been attributed to the same reaction (CAILL~RE, 1962). Under closely reproducible conditions, the detection limits and the effects on thermogram configuration of many carbonate minerals, caused by progressive artificial dilution with alundum, have been determined (WARNE,1963). The detection limits for siderite were between 2 5 5 % and 1-2% when determined in air and Nz, respectively. When determined in air, the thermogram shows a major modification for siderite contents between 30 and 40 % (by weight). Here, the increasing diminution of the endothermic peak, Ed.Z, becomes very marked; this gradually occurs with decreasing siderite content due to the progressive superposition of the stronger exothermic peak, Ex.2 (Fig. 17). At about 30 % siderite content, the resultant thermogram contains only a relatively small exothermic peak, because the exothermic peak, Ex.3, has become too weak to be recorded. With further decreases in siderite content, this single exothermic peak is so rapidly reduced in size that below 20 % it is recorded as a relatively insignificant feature. This confirms in detail the results of ROWLAND and JONAS (1949). In 0 2 this process is accelerated. Thus, the endothermic peak is completely suppressed even when 100 % siderite is present (ROWLAND and JONAS,1949; PAPAILHAU, 1958, 1959). The same effect was obtained by finely grinding the sample before D.T.A. analysis (ROWLAND and JONAS,1949). Magnesite ( M g c o 3 ) The available literature on magnesite D.T.A. is listed by SCHWOB (1950), WARNE (1962) SMYKATZ-KLOSS (1964). The D.T.A. and decomposition mechanisms of rhodochrosite have been described in detail by KULPet al. (1949) and KISSINCER
318
K . H. WOLF, A. J. EASTON AND S. WARNE
et al. (1956), and those of breunnerite and pistomesite by BECK(1950) and SCHWOB
(1 950).
The thermogram of magnesite, determined in air, is composed of a single large asymmetrical endothermic peak, due to the simple irreversible reaction: MgC03 +MgO C02 .T (SCHWOB, 1950). The peak temperature usually occurs between 660 and 700°C (Fig. 17). The additional small peaks sometimes recorded at higher temperatures (Fig.17, curve 19) have been attributed to the presence of small amounts of Ca, Feyand/or Mn. The formation of intermediate oxycarbonates as suggested by BRILL(1905) was not supported by X-ray and optical studies (BECK, 1950). The thermogram configuration is little affected by furnace atmosphere conditions (SCHWOB,1950; HAUL and HEYSTEK,1952; and WARNE,1963). The presence of only 1.xNaCl, however, lowers the peak temperature 50°C (BERG, 1943), and sharpens the initial inflection point (WEBBand HEYSTEK, 1957). The effects of progressive dilution are a gradual reduction in peak height, area, and temperature, whereas the detection limit is approximately 1% (Fig.17; WARNE, 1963).
+
Calcite (CaCO3) WEBBand HEYSTEK (1957) and WARNE (1963) have reviewed the literature on calcite D.T.A. In air or N2 the thermograms are similar, being composed of a single large asymmetrical endothermic peak caused by the reaction CaCOasCaO C02 t . The peak temperature generally occurs between 960 and 990°C. Evidence ranging from distortions to marked bifurcation of the calcite and (1950b), and aragonite endothermic peak, as figured by FAUST(1950), GRUVER WEBBand HEYSTEK (1957) has been attributed to the decomposition of two “types” of CaCO3 present: (1) primary calcite; (2) calcite formed by the inversion of aragonite. Thus, thermograms from samples containing mixtures of two calcites having markedly different crystallinity might be expected to show similar modifications. Determination in static or dynamic C02 atmospheres (ROWLAND and LEWIS, 1951; and WARNE,1963, respectively) displaces the endothermic peak up scale, thus increasing the peak temperature by about 60°C (Fig.18, curves 5 and 6). From a mixture of calcite and quartz, LIPPMAN (1952) recorded a small exothermic fluctuation due to wollastonite (CaSi03) formation, immediately following the “calcite” endothermic peak. This reaction was confirmed only when
+
Fig.17. D.T.A. curves of the major carbonates (siderite and magnesite) illustrating thermogram configuration and the effects of dilution and furnace atmosphere. Fig.18. D.T.A. curves of the major carbonates (calcite, aragonite, witherite, strontianite and dolomite) illustrating thermogram configuration and the effects of dilution and furnace atmosphere, and the difference between dolomite and a comparable mixture of magnesite plus calcite.
319 I , -2
mo
roo
mo
600
'
'
roi~c
5k5
%8
SIDERITE
30170
WLDMITE
2ibl
,9
MAGNESITE
_-------DETERMNED IN N ................. DETERMINED IN 0; 200
rpo
600
K
U
800
, lppopo'c
320
K. H. WOLF, A. J. EASTON AND S. WARNE
the constituents were very fine grained and intimately mixed (WARNE,1963). Thermograms from mixtures containing siderite or magnesite instead of calcite, contained no peaks attributable to Fe- or Mg-silicate formation. A gradual reduction in peak height, area and temperature results from progressive dilution; the detection limit is about 1 % (Fig.18; WARNE,1963). Aragonite group1 Aragonite (CaCO3) The thermograms of aragonite and calcite are similar, having a large endothermic peak caused by the same reaction: CaCOasCaO COZf . In addition, aragonite has a small endothermic peak between about 400 and 500°C due to the inversion of orthorhombic aragonite to trigonal calcite (Fig.18, curve 8). The latter small characteristic inversion peak is not detected when aragonite content is much below 35 %. This may vary considerably with the sensitivity of the D.T.A. unit used.
+
Witherite2 (BaCO3) and strontianite (SrCO3) The witherite and strontianite thermograms of CUTHBERT and ROWLAND(1947), GRUVER(1 950a), KAUFFMAN and DILLING (1 950), BARONet al. (1959), WARNE (1963), and SMYKATZ-KLOSS (1964) are in good agreement. The witherite thermogram is composed of two small sharp endothermic peaks (peak temperatures at about 820 and 980"C), due to reversible inversions from a to /l to y forms; whereas the cooling curve shows two similar exothermic peaks at somewhat lower temperatures due to y to /l to a inversions (Fig.18, curve 9). No decomposition takes place below 1,350"C. The thermogram of strontianite below 1,OOO"C is composed of a small sharp endothermic peak (approximate peak temperature is 930 "C) caused by an orthorhombic to trigonal inversion. Inasmuch as the latter is reversible, it shows as an exothermic peak on the cooling curve at about 850°C (Fig.18, curve 20). At temperatures above 1,000"C, endothermic decomposition starts, giving a peak temperature at about 1,200"C (WEBBand HEYSTEK, 1957). The presence of strontianite with calcite, endothermic peaks of which are usually superimposed, may be detected by the exothermic strontianite inversion peak on the cooling curve. If cooled in COz, however, this peak will be obscured by the recarbonation peak of calcite.
1 Cerussite has been
studied in detail by WARNE and BAYLISS (1962).
* Thermograms of bromlite, BaCa(CO&, and baryto-calcitehave been published by BECK(1950).
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
32 1
Dolomite group' Dolomite, C a M g ( C 0 3 ) ~ The available literature on dolomite D.T.A. is listed by SCHWOB ( I 950), GABINET (1959), WARNE (1962), and SMYKATZ-KLOSS (1964). Thermograms of dolomite determined in air or nitrogen are similar, being composed of two large endothermic peaks (Fig. 18, curve 18). The peak temperatures occur at approximately 800 and 950°C. It is generally accepted that the first and second endothermic peaks are caused by the dissociation of C02 from the ions in the Mg and Ca lattice positions, respectively. The first and second dolomite peaks occur at considerably higher and slightly lower temperatures than the corresponding peaks of magnesite and calcite (BECK, 1950). This enables one to differentiate dolomite from magnesite, calcite, or their mixture (Fig.18, curve 19). For dolomite+alcite mixtures, the CaC03 decomposition peaks of both minerals are usually superimposed, but the presence of considerable proportions of calcite may be inferred from the disproportionate enlargement of the resulting peak (Fig.18, curves 16 and 17; WARNE,1964). Occasionally, incomplete superposition results in a doubly terminating feature (SMYKATZ-KLOSS, 1964).The presence of salts, although greatly affecting the initial decomposition temperature, leaves the second peak unaltered (MURRAYet al., 1951). The D.T.A. of dolomite in C02 results in lowering and raising the first and second peak temperatures, respectively; whereas the cooling curve (in C02) shows only the exothermic recarbonation peak of calcite (Fig.18, curve 15). With progressive dilution, the peak sizes, areas and temperatures gradually decrease, but the second peak temperature falls more rapidly than the first. Thus, for dolomite contents below 20 % these peaks slowly coalesce to form a single peak. This is observable down to the detection limit of about 1 X(Fig.18; WARNE,1963). Ankerite, Ca(Mg,Fe) (CO3)z Ankerite thermograms (in air) contain three endothermic peaks, with peak temperatures generally occurring between 700-800 "C, 830-870 "C, and 930-950 "C, respectively. The first peak is sometimes followed by an exothermic reaction, which suppresses the immediately preceding and following peaks to a variable degree (cf. the published thermograms by GABINET, 1959; WARNE, 1962; and SMYKATZKLOSS, 1964). The increase in size of the second endothermic peak (not the first) with increasing Fez+content, and the production of a similar peak from a calcite-hematite For thermograms of huntite, MgCa(CO&, see FAUST (1953), KOBLENCZ and NEMECZ (1953), and BARON et al. (1959). 1
322
K. H. WOLF, A. J. EASTON AND S. WARNE
mixture (KULPet a]., 1951), apparently invalidates the mechanism of BECK(1951) and SMYKATZ-KLOSS (1964). According to KULP et al. (1951), dissociation at Mg positions in the lattice causes the first peak; MgO and FeO are released, the latter oxidizing immediately to y-FezO3 (exothermic). The Fez03.CaC03 formation produces the second endothermic peak (hence the dependence of the size of this peak on Fez+ content), whereas the dissociation of C02 from the Fe203.CaC03 and residual CaC03 produces the third endothermic peak. The end products were confirmed to be MgO and CaO.FezO3. Peak temperature differences enable one to distinguish ankerite from mixtures of siderite, magnesite and calcite (the presence o f a superimposed peak of calcite may be detected as described under dolomite) (Fig.20, curves I, 2 and 3). As previously described, siderite contents below 30% are best detected by using N2 atmosphere. Progressive dilution effects are similar to those of dolomite, except that all three peaks coalesce for ankerite contents much below 20% (Fig.19). The determination in COz results in greater peak separation than shown by dolomite (Fig.19, curve 5).
ANKERITE +CALCITE (I :I)
ANKERlTE +OOLOMITE +AI2O3 (2:1:1)
-DETERMINED 200
Fig.19.
400
--
-
IN AIR SO0
Fig.20.
Fig.19. Thermograms (D.T.A.) of ankerite showing the effects of dilution and futnace atmosphere. Fig.20. Thermograms (D.T.A.) of mixtures of carbonates minerals.
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
323
Mixtures of carbonates Thermograms (in air) of bimineralic (1 : I ) artificial mixtures of the above described nine carbonates show no evidence of interaction. The effects of all carbonate peaks can be recognized even for dolomite-ankerite mixtures (Fig.20, curve 4), although superposition of some peaks does occur (WARNE,1963). Even though no detailed study of mixtures of all these carbonates in various proportions was made, it is concluded that they are detectable in mixtures by D.T.A. Detection limits should be similar to those established for the individual mineral-dilution sequences. Due to peak coalescence, the detection limits of dolomite or ankerite in mixtures may be somewhat higher. With the exception of siderite-rhodochrosite mixtures, this conclusion is supported by the limited number of studies on carbonate mixtures (KULPet al., 1949, 1951; FAUST,1953; KOBLENCZ and NEMECZ,1953; CAPDECOMME and PWLOU,1954; WEBBand HEYSTEK, 1957; and WARNE,1964). Problems arising from the confusing multiplicity of peaks exhibited by samples containing several minerals are greatly reduced by using the double D.T.A. method Of GR~MSHAW et al. (1945) or D.T.A. of artificial mixtures. Further D.T.A. data on the minerals which may occur in relatively minor amounts in carbonate rocks are presented by MACKENZIE (1957). THERMOGRAVIMETRIC ANALYSIS
Thermogravimetric analysis (T.G.A.), the continuous record of weight changes produced by heating a sample at a constant rate, is complementary to D.T.A. as it provides continuous weight variation data relatable to the D.T.A. peaks. The variations in the rate of weight change are often recorded only as lines having slightly different slopes on T.G.A. curves, also called thermobalance curves, although considerable improvement is indicated by determination in self-generating atmospheres (GARNand KESSLER,1960; GARN,1961). Simultaneous determinations of T.G.A. and D.T.A. curves are described by KISSINGER et al. (1956) and PAPAILHAU (1959). SCHWOB (1950) studied the Fe, Mg, and Ca carbonates covering the effects of NaCl, flux, and atmospheres of air, COZ and water vapor. PAPAILHAU (1959), CAILLI~RE and POBEGUIN (1960), CAILL~RE (1962), and WARNE(1963) presented additional curves. (See KISSINGER et al., 1956, and WARNEand BAYLISS,1962, for data on rhodochrosite and cerussite.) For reference, T.G.A. curves of the carbonate minerals used for D.T.A., except strontianite and witherite (the T.G.A. curve of aragonite is identical with that of calcite), are included here in Fig. 21. They were determined on using a continuously weighing Stanton thermobalance reading to 1 mg, and 1.00 g samples at - 100 mesh (B.S.S.). The heating rate was 5.5 "C/min. Diagnostically different curves are presented for: ( I ) magnesite, (2) siderite, (3) dolomite and ankerite, and (4) calcite. Although thermogravimetric studies of carbonate
324
K. H. WOLF, A. J. EASTON AND S. WARNE i
"
"
"
"
"
"
"
"
"
1
TEMPERATVRE(~C)
Fig.21. Curves illustrating the T.G.A. of siderite, rnagnesite, calcite, dolomite and ankerite, the D.T.A. curves of which are shown in Fig.17-20.
mixtures have not been made, the detection of reasonable proportions of these minerals in bimineralic mixtures, with the exception of dolomite and ankerite or calcite with dolomite or ankerite, appears likely. The anticipated detection limits by T.G.A. would be considerably higher than those by D.T.A.
X-RAY DIFFRACTION
Amongst the many descriptions of the experimental methods and techniques for X-ray diffraction those of AZAROFF and BUERGER (1958), BRINDLEY (1961), and GRAFand GOLDSMITH (1963) provide a good coverage. The diffraction patterns of the carbonate and associated minerals in carbonate rocks are diagnostically different and their identification is made by reference to suitable collations of X-ray diffraction data, such as the A.S.T.M. X-ray powder data index (BROWN,1961). Data for the rhombohedra1 carbonates specifically was presented by GRAF(1961). Despite the multiplicity of diffraction lines or peaks, the constituents of mixed carbonates may be identified by various X-ray diffraction techniques. From the relative intensities of the strongest diffraction lines of dolomite and calcite (determined by diffractometer examination of fine powders in a cell type holder), their percentage contents may be read off from the calibration curve of TENNANT and BERGER (1957). This is considered to apply equally well to dolomite-
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
325
magnesite mixtures. The adaptations to polished rock slices and plastic bonded grain mounts were described by HUGHES et al. (1960) and WEBER and SMITH(1961). The detection limit of 5 % suggested by these workers also applies to magnesite, siderite, rhodochrosite and minerals commonly associated with them which they listed; whereas albite, gypsum and polyhalite may produce interfering reflections. and LEMISH (1960) The description of a wet chemical X-ray method by HILTROP has been followed by a detailed appraisal of this and other X-ray methods previously applied to the determination of the calcite, dolomite, quartz and clay et al. (1963). For the quantitative detercontents of carbonate rocks by DIEBOLD mination of calcite, dolomite and quartz, the quantitative and qualitative evaluation of the clay mineral fraction, and the composition of calcite and dolomite, they recommended the following four procedures: ( I ) an internal standard method modelled after ALEXANDER and KLUG (1 959); (2) a subtraction method described by them; (3) clay separation and X-ray diffraction; and (4) a modified method after HARKER and TUTTLE (1955). Furthermore, the merits of both the “Tennant and Berger” and “Hiltrop and Lemish” methods were evaluated. By measuring integrated line intensity in place of peak intensity, DAVIES and HOOPER(1963) achieved a detection limit of 1 % for calcite or aragonite in mixtures of the two. The composition of individual members of the dolomite, ferroan dolomite, ankerite series can be obtained from the diffraction data of H o W l E and BROADHURST (1958) and GOLDSMITH et al. (1 962). ROSENBERG (1963) established the relationship of variation in 2 0 with composition for the systems MgC03-FeC03 and MnC03FeC03. GRAFand GOLDSMITH (1955) established the relationship between the composition of magnesian calcites and calcian dolomites and their unit-cell edges. This led to its detailed application by SKINNER (1963) and to an improved method of measurement of small changes in the lattice spacings of calcites, with particular reference to Mg2+substitution (WAITE,1963). By employing the techniques of CHAVE (1 954) and GOLDSMITH et al. (1955), TAFTand HARBAUGH (1964) constructed calibration curves from which the proportions of aragonite, low-Mg calcite and high-Mg calcite may be determined from the ratio of the intensity of their diffraction peaks. X-ray diffraction studies thus provide, within the limits described by the various authors, suitable methods for the rapid evaluation of the minerals present in carbonate rocks. Interesting to note in this regard is the observation made by GOTO (1961, p.614) that vaterite and Ca-bearing strontianite have properties that may cause them to be confused with aragonite; and, in addition, their sensitivity to chemical tests, such as Meigen’s reaction, resemble that of aragonite. HOOPER (1964) described the method of electron probe X-ray microanalysis for the determination of trace elements, as exemplified on Foraminifera, and discussed its advantages as compared to other techniques.
326
K. H. WOLF, A. J. EASTON AND S. WARNE
THERMOLUMINESCENCE OF CARBONATES
Certain minerals such as calcite, dolomite, fluorite, and potash feldspar, for example, emit light when heated to temperatures below that of incandescence. A specimen emits this light (“thermoluminescence”) only once, and it has to be exposed to X-rays or y-rays before a second heating will produce thermoluminescence. According to DANIELS et al. (1953), natural carbonates previously exposed to 6OCo radiation show four temperature peaks: a t 120-140°, 150-190”, 210-250”, and 290-310°C. The two lower peaks are often not observed because ambient temperatures are usually high enough to cause a shift of electrons from their traps. ZELLER and PEARN(1960), however, were able to observe the 125°C peak in refrigerated Antarctic limestone specimens. For the theory that explains thermoluminescence and the experimental procedures, the reader may consult the numerous readily available publications by DANIELS et al. (1953), PARKS(1953), SAUNDERS (1 953), ZELLER (1954), BERGSTROM (1956), LEWIS(1956b), PITRAT(1956), ZELLERet al. (1957), DANIELS (1958), ANGINO and SIEGEL (1959), JOHNSON (1960), and SIEGEL (1963). In numerous instances the various investigators have suggested that thermoluminescence may be a useful tool in practical and research geology. It has been found, however, that the glow curves of carbonate sediments “represent an algebraic total of diverse physical and chemical influences” (BERGSTROM, 1956)such as: mineralogy (OCKERMAN and DANIELS, 1954; LEWIS,1956b; ZELLER and WRAY, 1956; MOORE,1957; RIEKE,1957; DANIELS, 1958; and JOHNSON, 1960), polymorphism (ZELLER and WRAY,1956; and JOHNSON, 1960), ratio of minerals present (LEWIS,1956b; PITRAT, 1956; JOHNSON, 1960; and INGERSON, 1962), trace elements or “impurities” (PITRAT,1956; ZELLERand WRAY,1956; ZELLERet al., 1957; DANIELS, 1958;and JOHNSON, 1960),exposure to radioactive material (DANIELS et al., 1953;PARKS, 1953;SAUNDERS, 1953; LEWIS,1956b; PITRAT, 1956;ZELLERetal., 1957; and DANIELS, 1999, heating (MOORE,1957; INGERSON, 1962; and MCDIARMID, 1963), pressure (ZELLERet al., 1955, 1957; DANIELS, 1958; BARNES, 1959; and INGERSON, 1962), recrystallization and inversion (MOORE,1957; ZELLERet al., 1957; DANIELS, 1958; JOHNSON, 1960; and INGERSON, 1962), and geologic history and diagenesis in general (SIEGEL,1963). As some of these factors increase and others reduce the type and degree of luminescence, and because more than one factor can be influential at the same time or be effective in successive stages, it is not surprising that seemingly contradictory results have been obtained. Nevertheless limited success has been achieved: (I) in age determination (ZELLER,1954; ZELLER et al., 1955, 1957); (2) in correlating and zoning carbonate sediments (PARKS,1953; SAUNDERS, 1953; BERGSTROM, 1956, LEWIS,1956; PITRAT,1956; DANIELS, 1958); (3) for measuring calcite-dolomite contents (LEWIS,1956; PITRAT,1956); (4) in determining origin of dolomites (SIEGEL,1963); (5) in the study of biogenic calcium carbonate (JOHNSON, 1960);
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
327
and (6) in the investigation of temperature and pressure histories (HANDINet al., 1957; ANGINO,1959). On the other hand, many similar studies have indicated that despite the occasional successful application of thermoluminescence, it is not a reliable tool as yet and more basic research is required as has been pointed out by most of the investigators. (See also Hsu, 1967.)
RADIOCARBON DATING OF CARBONATE SEDIMENTS
The dating of sediments by the 14C method has been described, for example, by LIBBY(1955), RANKAMA (1956), EMERYand BRAY(1962) and ~ S T L U N Det al. (1962). This is an invaluable tool for determining the approximate absolute age of recent carbonate deposits; it is particularly useful, therefore, in measuring the rates of sedimentation. A number of modifying influences exist, however, that cause either an increase or decrease of apparent ages because of dilution and alteration effects. Charcoal, well-preserved wood, and peat sometimes prove to be more reliable for 14C dating. In any case, there are cosmic controls that lead to variations in 14C productivity by as much as 2 %. TAFTand HARBAUGH (1964, p. 113) recently discussed the discrepancies between radiocarbon ages of different components in carbonate sediments. Both carbonate carbon and organic carbon were analyzed. “Of ten samples, six yielded greater ages for carbonate carbon in respect to organic carbon, three yielded smaller ages for carbonate carbon in respect to organic carbon, and one yielded the same age for carbonate carbon in respect to organic carbon.” The reasons for the differences in radiocarbon ages of carbonates and organic carbons are poorly understood, but they suggested four possible reasons (see also FAIRBRIDGE, 1961). (I) In analyzing carbonate sediments it is possible that the material consists of particles derived from different geographic sources and rocks that vary in age. TAFTand HARBAUGH (1964, p.113) gave an example of this. A similar case has been pointed out by EMERY and BRAY(1962), and WOLF(1965a,c). (2) Another possibility is that the organisms used carbon deficient in 14C in comparison to the proportion of 14C in the atmosphere. For example, “old” carbonate carbon may reach the environment in which the organisms live via rivers that drain land areas with ancient carbonate rocks. Thus, 14C deficiency causes the skeleton to appear older than it is in reality. (3) Burrowing organisms such as burrowing clams and worms may contribute younger organic material to buried sediments. (4) Many animals take in finely divided carbonate particles with their food, and if the organisms absorb some of the carbonate particles that may have “older” carbonate carbon (see I) and secrete skeletal carbonate, the 14Cdates of the latter may be anomalous. EMERY(1960) and EMERY and BRAY(1962) have dated different fractions
328
K. H.
WOLF, A.
J. EASTON AND S. WARNE
of the samples collected, namely, Foraminifera, fine-grained carbonate, total carbonate, and extracted carbon. These two investigators concluded “. . . after considering the various pieces of evidence . that the total organic carbon is the most reliable dating medium for the basins off Southern California.” Other possible modifying factors that increase or decrease the apparent ages determined by 14C method are discussed by KEITHand ANDERSON (1963) and RUBINet al. (1963). The former concluded that the errors in determining radiocarbon dates of shell material may be as large as several thousand years. BERGER et al. (1964), however, indicated that conchiolin of shells, similar to collagen in bones, can be prepared for dating; this may give more reliable results than dating of the calcium-carbonate shell material, because secondary changes are less likely to occur in conchiolin than in the carbonate skeleton. The published results indicate that the interpretation of radiocarbon age dates, in particular in the case of the 14Cmethod, is still marked by many uncertainties. Aside from determining the precise half-life of 14C, which was assumed as being 5,568 f 30 years by LIBBY(1955), but now raised to 5,730 f 40’years (see GODWIN,1962), many primary and secondary factors that control the radiocarbon content are poorly understood. Continued emphasis on research concerning the basic problems, no doubt, will increase the reliability of 14C dating of carbonate sediments. It should also be mentioned that research is in progress on the use of traces of uranium, helium, protactinium, and thorium in carbonates for absolute age 1959; BROECKER, 1963; THURBER et al., determination (TATSUMOTO and GOLDBERG, 1963; FANALE and SCHAEFFER, 1964).
..
ISOTOPE INVESTIGATIONS OF CARBONATE SEDIMENTS
Isotope investigations are being made at an ever-increasing rate in solving problems in carbonate rock petrology. Most of the work has been conducted on the ratios of 1 8 0 / 1 6 0 and 13C/W, and in isolated cases on 24Mg/26Mg(and also 48Ca/Wa/ (total Ca) ratios). Some of the more recent papers that describe the theory of isotope fractionation and analytical procedures, and provide references to earlier publications, are those by MCCREA(1 950), CRAIG(1953), JEFFERY et al. (1959, RANKAMA (1956), CLAYTON and EPSTEIN(1958), and DAUGHTRY et al. ( 1962). Although considerable information is available on the elemental distribution of Sr (WOLFet al., 1967), only a few investigations appear to have been made on its isotopes. WICKMAN (1948), KULP(1950), and KULPet al. (1952) suggested a possible use of Sr isotopes for age determination. On the other hand, HERZOG et al. (1953) indicated that it would be difficult to use strontium for that purpose (see RANKAMA, 1956, p.337).
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
329
Investigations of 13C/"T ratio have been used: (I) to distinguish between marine and fresh-water or terrestrial calcareous material (CRAIG,1953; CLAYTON and DEGENS, 1959; J. C. VOGEL,1959; LOWENSTAM, 1961; DEGENS and EPSTEIN, 1962b, 1964; KEITHand ANDERSON, 1962;LLOYD,1964; WEBER,1964; WEBER et al., 1964); (2) in studies of dolomite genesis and limestone petrology (DEGENS and EPSTEIN, 1962a, 1964; Ross and OANA,1961;WILLIAMS and BARGHOORN, 1963); (3) to study calcareous varves (WEBER,1964); and (4) in investigating diagenetically altered carbonates (WICKMAN and VONUBISCH,1951; JEFFERYet al., 1955; COMPSTON, 1960; Ross and OANA,1961; WEBER and ROCQIJE, 1963; DEGENS and EPSTEIN, 1964; GROSS, 1964; LLOYD,1964). A number of the isotope studies revealed phylogenetic differences of faunal and floral calcium carbonate (CRAIG, 1953, 1954; REVELLE and FAIRBRIDGE, 1957; LOWENSTAM, 1961; KEITHand ANDERSON, 1962; GROSS,1964; LLOYD,1964; TAFTand HARBAUGH, 1964). The isotope studies undertaken by LOWENSTAM and EPSTEIN(1957) suggested that many of the Recent aragonite needle deposits may have been formed,by the disintegration of calcareous Algae. Similar approaches may assist in discriminating for example between algal, bahamite, and faecal pellets. The ratio 1 8 0 / 1 6 0 has been utilized: (I) in establishing paleotemperatures (UREYet al., 1951; EPSTEIN et al., 1953; CLAYTON and EPSTEIN, 1958; FLUGEL and FLUGEL-KAHLER, 1963; EMILIANI, 1964; LLOYD,1964); (2) in distinguishing between syngenetic, diagenetic, hydrothermal and metamorphic carbonates (ENGELet al., 1958; DEGENS and EPSTEIN, 1964); (3) in ore investigations (ENGELet al., 1958); (4) in dolomite studies (DEGENS and EPSTEIN, 1962a, 1964); (5) in general petrogenesis and diagenesis of carbonate sediments (CLAYTON and EPSTEIN, 1958; DEGENS and EPSTEIN,1962a, 1964; FLUGELand FLUGEL-KAHLER, 1963; GROSS,1964; WEBER,1964); and (6) in the discrimination between marine and fresh-water sediments (DEGENS and EPSTEIN, 1962a, 1964). Differences in oxygen-isotope composition of some right- and left-coiled Foraminifera and their influence on the accuracy of isotope data are discussed by LONGINELLI and TONGIORGI (1964). DAUGHTRY et al. (1962) have shown that future work on magnesium isotopes may prove to be a valuable approach in solving genetic problems of dolomites and possibly other Mg-containing carbonates. Finally, 45Ca has been used in determining the mode, location, rate, and amount of calcium carbonate deposition by a number of shell-forming organisms (BEVELANDER, 1952; WILBURand JODREY, 1952; JODREY, 1953). More detailed information on isotope studies related to carbonate mineralogy and petrology is given by DEGENS (1967).
330
K. H. WOLF, A. J. EASTON AND S. WARNE
REFERENCES
ALEXANDER, L. E. and KLUG,P. H., 1959. X-Ray Diffraction Procedures, 2 ed. Wiley, New York, N.Y., 716 pp. ANGINO, E. E., 1959. Pressure effects on thermoluminescence of limestone relative to geologic age. J. Geophys. Res., 64: 569-573. ANGINO, E. E. and SIEGEL,F. R., 1959. The effects of trace elements on natural thermoluminescence. Compass, 36: 296-303. G., KJELLBERG, G. and LIBBY,W. F., 1951. Age determination of Pacific chalk ooze ARRHENIUS, by radiocarbon and titanium content. Tellus, 3: 222-229. AZ~ROFF, L. V. and BUERGER, M. J., 1958. The Powder Method in X-Ray Crystallography. McGrawHill, New York, N.Y., 342 pp. BANKS,J. E., 1950. Particle-type well logging. Bull. Am. Assoc. Petrol. Geologists, 34: 1729-1736. BARLETT, H. H., 1951. Radiocarbon datability of peat, marl, caliche and archeological materials. Science, 114: 55. BARNES, V. E., 1959. Thermoluminescence of Pre-Simpson Paleozoic rocks. In: V. E. BARNES, P. E. CLOUD,L. P. DIXON JR., R. L. FOLK, E. C. JONAS,A. R. PALMER and E. J. TYNAN (Editors), Stratigraphy of the Pre-Simpson Paleozoic Subsurface Rocks of Texasand Southeast New Mexico-Wniv. Texas, Publ., 5924: 293 pp. G., CAILLBRE, S.,LAGRANGE, R. et POBEGUIN, TH.,1959. Etude du Mondmilch de la Grotte BARON, de la Clamouse et de quelques carbonates et hydrocarbonates Alcalino-Terreuk. Bull. Soc. Franc. Mindral. Crist., 82: 150-158.
BAYLISS, P., 1964. Effect of particle size on differential thermal analysis. Nature, 201: 1019. BAYLISS, P. and WARNE,S., 1962. The effects of controllable variables on differential thermal analysis. Am. Mineralogist, 47: 775-778. BEALES, F. W., 1960. Limestone peels. J. Alberta SOC.Petrol. Geologists, 8: 132-135. BECK,C. W., 1950. Differential thermal analysis curves of carbonate minerals. Am. Mineralogist, 35: 985-1013.
BERG,L. G., 1943. Influence of salt on the dissociation of dolomite. Dokl. Akad. Nauk S.S.S.R., 38: 24-27.
BERGER, R., HORNEY, A. G. and LIBBY,W. F., 1964. Radiocarbon dating of bone and shell from their organic components. Science, 144 (3621): 999-1001. BERGSTROM, R. E., 1956. Subsurface correlation of some Pennsylvanian limestones of the Midcontinent by thermoluminescence. Bull. Am. Assoc. Petrol. Geologists, 40: 918-942. BERRY,L. G. and MASON,B., 1959. Mineralogy, Descriptions, Determinations. Freeman, San Francisco, Calif., 630 pp. G., 1952. Calcification in molluscs. 111. Intake and deposition of 45Ca and 32P in BEVELANDER, relation to shell formation. Biol. Bull., 102: 9-15. BISQUE, R. E., 1961. Analysis of carbonate rocks for calcium, magnesium, iron, and aluminium with E.D.T.A. J. Sediment. Petrol., 31: 113-122. BISQUE,R. E. and LEMISH,J., 1958. Chemical characteristics of some carbonate aggregate as related to durability of concrete. Highway Res. Board, Bull., 196: 129-145. BISQUE,R. E. and LEMISH, J., 1959. Insoluble residue-magnesium content relationship of carbonate rocks from the Devonian Cedar Valley Formation. J. Sediment. Petrol., 29: 73-76. BISSELL, H. J., 1957. Combined preferential staining and cellulose peel technique. J. Sediment. Petrol,, 27: 417-420.
BLOSS,F. D., 1961. An Introduction to the Methods of Optical Crystallography. Holt, Rinehart and Winston, New York, N.Y., 294 pp. BOUMA,A. H., 1962. Sedimentology of some Flysch Deposits. A Graphic Approach to Facies Interpretation. Elsevier, Amsterdam, 168 pp. BRADLEY, D. E., 1954. Evaporated carbon films for use in electron microscopy. Brit. J. Appl. Phys., 5 : 65-66. BRADLEY, D. E., 1960. Replica techniques in applied electron microscopy. J. Roy. Microscop. SOC.,79: 101-118.
BRADLEY, W. F., BURST,J. F. and GRAF,D. L., 1953. Crystal chemistry and differential thermal effects of dolomite. Am. Mineralogist, 38: 207-218.
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
33 1
BRILL,O., 1905. Ober die Dissoziation der Karbonate der Erdalkalien und des Magnesiankarbonates. Z. Anorg. Allgem. Chem., 45: 285. BRINDLEY, G. W., 1961. Experimental methods. In: G. BROWN(Editor), The Identification and Crystal Structures of Clay Minerals. Mineral. Soc.(Clay Mineral Group), London, pp. 1-50. BROECKER, W. S., 1963. A preliminary evaluation of uranium series inequilibrium as a tool for absolute age measurement on marine carbonates. J. Geophys. Res., 68: 2817-2834. BROECKER, W. S. and ORR,P. C., 1958. Radiocarbon chronology of Lake Lahontan and Lake Am., 69: 1009-1032. Bonneville. Bull. Geol. SOC. BROWN,G. (Editor), 1961. The X-ray Identification and Crystal Structures of Clay Minerals. Mineral. SOC.(Clay Mineral Group), London, 544 pp. BUEHLER, E. J., 1948. The use of peels in carbonate petrology. J. Sediment. Petrol., 18: 71-73. BURGER, D., 1963. Notes on some carbonate minerals in the iron ore deposits of the Iron Duke Area, South Middleback Range, South Australia. Australian lnst. Mining Met. Proc., 208: 55-80. CAILLZRE, S., 1962. Rappel de la signification des phknomtnes thermiques ii propos de I’ttude de la sidbose. Bull. Soc. Franc. Mineral. Crist., 85: 122-124. CAILL~RE, S. et POBEGUIN, TH., 1960. Contribution ii l’ktude des carbonates simples anhydres. Bull. Sor. Franc. Mineral. Crist., 83: 3641. CALVERT, S. E. and VEEVERS, J. J., 1962. Minor structures of unconsolidated marine sediments revealed by X-radiography. Sedimentology, 1 : 287-295. L. et PULOU,R., 1954. Nouveau dispositif d’analyse thermique difftrentielle. CAPDECOMME, Bull. Sor. Franc. Mineral. Crist., 17: 969-973. CAROZZI, A. V., 1950. Contribution A l’ktude des rythmes de sedimentation. Arch. Sci. (Geneve), 3: 1740,95-146. CAROZZI,A. V., 1958. Micromechanisms of sedimentation in the epicontinental environment. J. Sediment. Petrol., 28: 133-150. CHAVE, K. E., 1954. Aspects of the biochemistry of magnesium. 2. Calcareous sediments and rocks. J. Geol., 62: 587-599. CHENG,K. L., KURTZ,T. and BRAY,R. H., 1952. Determination of calcium, magnesium and iron in limestones. Anal. Chem., 24: 1640-1644. CHILINGAR, G. V. and TERRY,R. D., 1954. Simplified technique of determining calcium and magnesium content of carbonate rocks. Petrol. Engr., 26 (12): 368-370. CHILINGAR, G. V., BISSELL, H. J. and WOLF,K. H., 1967. Diagenesis of carbonate rocks. In: G. LARSEN and G. V. CHILINGAR (Editors), Diagenesis in Sediments. Elsevier, Amsterdam, in press. CLAYTON, R. N., 1959. Oxygen-isotope fractionation in the system carbonate-water. J. Chem. Phys., 30: 1246-1250. CLAYTON, R. N. and DEGENS, E. T., 1959. Use of carbon-isotope analyses for differentiating freshwater and marine sediments. Bull. Am. Assoc. Petrol, Geologists, 43: 89G897. CLAYTON, R. N. and EPSTEIN,S., 1958. The relationship between 1sO/160ratios in coexisting quartz, carbonate and iron oxides from various geological deposits. J. Geol., 66: 352-373. CLOWES, F. and COLEMAN, J. B., 1944. Quantitative Chemical Analysis, 15 ed. Churchill, London, 90 PP. COMPSTON, W., 1960. The carbon isotopic compositions of certain marine invertebrates and coals from the Australian Permian. Geochim. Cosmochim. Arta, 18: 1-22. CRAIG,H., 1953. The geochemistry of the stable carbon isotopes. Geochim. Cosmochim. Acta, 3: 53-92. CRAIG,H., 1954. Carbon-13 in plants and the relation between carbon-13 and carbon-I4 variations in nature. J. Geol., 62: 115-149. CUVILLIER, J., 1951a. Correlations Stratigraphiques par Microfacies en Aquitaine Occidentale. Brill, Leiden, 34 pp. J., 1951b. Abstract of Cuvillier (1951a), and discussion by Henson, Thomas, and CUVILLIER, Reichel. World Petrol. Congr., Proc., 3rd, The Hague, 1951, Sect. I , Geol. Geophys., pp.44W8. F. L. and ROWLAND, R. A., 1947. Differential thermal analysis of some carbonate CUTHBERT, minerals. Am. Mineralogist, 32: 1 1 1-1 16.
3 32
K . H. WOLF, A. J. EASTON AND S. WARNE
D’ALBISSIN, M. et DE RANGO,C., 1962. Etude de la microstructure des roches calcaires par I’observation au microscope Clectronique de I’orientation de figures de corrosion. Bull. SOC.Franc. MinPral. Crist., 85: 170-176. F., 1958. Thermoluminescence analysis. In: J. D. HAUNand L. W. LEROY(Editors), DANIELS, Subsurface Geology in Petroleum Exploration. Colo. School Mines, Golden, Colo., pp. 179-202. D. F., 1953. Thermoluminescence as a research tool. DANIELS, F., BOYD,C. A. and SAUNDERS, Science, 1 17: 343-349. M., 1962. Magnesium isotopic distribution in doloDAUGHTRY, A. C., PERRY,D. and WILLIAMS, mite. Geochim. Cosmochim. Acta, 26: 857-866. DAVIES, T. T. and HOOPER,P. R., 1963. The determination of the calcitelaragonite ratio in mollusc shells by X-ray diffraction. Mineral. Mag., 33: 608-612. DEAN,J. A., 1960. Flame Photometry. McGraw-Hill, New York, N.Y., 354 pp. DEER, W. A., HOWIE,R. A. and ZUSSMAN, J., 1962. Rock-forming Minerals. 5. Non-silicates. Longmans, London, 371 pp. E. L., 1962. Absence of carbon-14 activity in dolomite from Florida DEFFEYES, K. S.and MARTIN, Bay. Science, 136 (3518): 782. DEGENS, E. T., 1967. Stable isotope distribution in carbonates. In: G. V. CHILINGAR, H. J. BISSELL (Editors), Carbonates Rocks, B. Elsevier, Amsterdam, pp. 193-208. and R. W. FAIRBRIDGE DEGENS,E. T. and EPSTEIN,S., 1962a. Stable isotope studies on marine and continental dolomites from Recent and ancient sediments. Geol. SOC.Am., Spec. Papers, 68: 160-161 (abstract). S., 1962b. Relationship between 180/160 ratios in coexisting carbonDEGENS, E. T. and EPSTEIN, ates, cherts and diatomites. Bull. Am. Assoc. Petrol. Geologists, 46: 534-542. S., 1964. Oxygen and carbon isotope ratios in coexisting calcites and DEGENS, E. T. and EPSTEIN, dolomites from Recent and ancient sediments. Geochim. Cosmochim. Acta, 28: 2 3 4 . E. G. and KEITH,M. L., 1958. Environmental studies of Carboniferous DEGENS, E. T., WILLIAMS, sediments. 2. Application of geochemical criteria. Bull. Am. Assoc. Petrol. Geologists, 42: 981-987. DE VRIES, H., 1959. Measurement and use of natural radio-carbon. In: P. H. ABELSON (Editor), Researches in Geochemistry. Wiley, New York, N.Y., 511 pp. DIAMOND, J. J., 1955. Flame photometric determination of strontium in Portland cement. Anal. Chem., 27: 913-915. DIEBOLD, F. E., LEMISH, J. and HILTROP, C. L., 1963. Determination of calcite, dolomite, quartz and clay content of carbonate rocks. J. Sediment. Petrol., 33: 124-139. EASTON, A. J., 1964. The determination of chromium in the presence of manganese in rocks and minerals. Anal. Chim. Acta, 31: 189-191. L., 1963. The determination of titanium in meteoritic material. EASTON, A. J. and GREENLAND, Anal. Chim. Acta, 29: 52-55. EASTON, A. J. and LOVERING, J. F., 1963. The analysis of chondritic meteorites. Geochim. Cosmochim. Acta, 27: 753-767. J. F., 1964. Determination of small quantities of potassium and EASTON, A. J. and LOVERING, sodium in stony meteoritic material, rocks and minerals. Anal. Chim. Acta, 30: 543-548. EASTON,W. H., 1942. An improved technique for photographing peel sections of corals. J. Paleontol., 16: 261-263. J. and WILSON,J., 1964. A quantitative separation of non-carbonate minerals from ELLINGBOE, carbonate minerals. J. Sediment. Petrol., 34: 412-418. EMERY, K. O., 1960. The Sea off Southern California. A Modern Habitat of Petroleurn. Wiley, New York, N.Y., 366 pp. EMERY, K. 0. and BRAY,E. E., 1962. Radiocarbon dating of California Basin sediments. Bull. Am. Assoc. Petrol. Geologists, 46: 1839-1 856. EMILIANI, C., 1964. Paleotemperature analysis of the Caribbean cores A-254-BR-C and CP-2F. Bull. Geol. SOC.Am., 75: 129-144. G., 1953. Tertiary ocean-bottom temperatures. Nature, 171: EMILIANI, C. and EDWARDS, 878-888. ENGEL,A. E. J., CLAYTON, R. N. and EPSTEIN, S., 1958. Variations in isotopic composition of
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
333
oxygen and carbon in Leadville limestone and its hydrothermal and metamorphic phases. J. Geol., 66: 374-393. EPSTEIN, S., 1959. The variations of the 1*0/160 ratio in nature and some geologic implications. In: P.H. ABELSON (Editor), Researches in Geochemistry. Wiley, New York, N.Y., pp.217-240. EPSTEIN,S., BUCHSBAUM, R., LOWENSTAM, H. A. and UREY,H. C., 1953. Revised carbonatewater isotopic temperature scale. Bull. Geol. SOC.Am., 64: 1315-1 326. EPSTEIN,S., GRAF,D. L. and DEGENS, E. T., 1963. Oxygen isotope studies on the origin of dolomite. In: H. CRAIG,S. L. MILLERand G. T. WASERBURG (Editors), Isotopic and Cosmic Chemistry. North Holland, Amsterdam, pp. 169-1 80. ERICSON,D. B. and WOLLIN,G., 1956. Micropaleontological and isotope determinations of Pleistocene climates. Micropaleontology, 2: 257-270. EVAMY, B. D., 1963. The application of a chemical staining technique to a study of dedolomitization. Sedimentology, 2: 164170. FAIRBANKS, E. E., 1925. A modification of Lemberg’s staining methods. Am. Mineralogist, 10: 126-127. FAIRBRIDGE, R. W., 1954. Stratigraphic correlation by microfacies. Am. J. Sci., 252: 683-694. FAIRBRIDGE, R. W., 1961. Eustatic changes in sea level. In: L. H. AHRENS, F. PRESS, S. K. RUNCORN,and H. C. UREY(Editors), Physics and Chemistry ofthe Earth. Pergamon, London, 4: 99-185. FANALE, F. P. and SCHAEFFER, 0. A., 1964. Dating of fossil aragonite shells and corals by the U-He method. Geol. SOC.Am., Prop. Ann. Meeting, 1964, p.59. FAUST, G. T., 1950. Thermal analysis studies on carbonates. 1 . Aragonite and calcite. Am. Mineralogist, 35 : 207-224. FAUST, G. T., 1953. Huntite, MgCa(CO&, a new mineral. Am. Mineralogist, 38: 4-24. FEIGL, F., 1954. Spot Tests in Inorganic Analysis, 4 ed. Elsevier, Amsterdam, 518 pp. FEEL,F., 1958. Spot Tests in Inorganic Analysis, 5 ed., Elsevier, Amsterdam, 600 pp. FLASCKA, H., 1953. Direct volumetric determination of divalent manganese with E.D.T.A. in presence of other metals. Chem. Anal., 42: 56-58. FLUGEL,E. und FLUGEL-KAHLER, E., 1962. Mikrofazielle and geochemische Gliederung eines obertriadischen Riffes der nordlichen Kalkalpen. Mit t . Museum Bergbau Geol., Tech. Landesmuseum “Joanneum” (Graz), 24: 129 pp. FOLK, R. L., 1962. Sorting in some carbonate beaches of Mexico. Trans. N.Y. Acad. Sci., 25: 222-244. FOLK,R. L. and ROBLES, R., 1964. Carbonate sands of Isla Perez, Alacran Reef Complex, Yucatan. J. Geol., 72: 255-292. FOLK,R. L., HAYES,M. 0. and SHOJI,R., 1962. Carbonate sediments of Isla Mujeres, Quintana Roo, Mexico and vicinity. Guidebook Field Trip Peninsula Yucatan, New Orleans Geol. SOC.,pp. 85-101). FRIEDMAN, G . M., 1959. Identification of carbonate minerals by staining methods. J. Sediment. Petrol., 29: 87-97. GABINET, M. P., 1959. On the dolomites and siderites of the Menilite Series of the Soviet Carpathians. Mineralog. Sb., L’vovsk. Geol. Obshchestvo pri L‘vovsk. Gos. Univ., 13: 349-361. GARN,P. D., 1961. Thermal analysis-a critique. Anal. Chem., 33: 1247-1251. GARN,P. D. and KESSLER, J. E., 1960. Thermogravimetry in self-generating atmospheres. Anal. Chem., 32: 1563-1565. GAULT,H. R. and WEILER,K. A., 1955. Studies on carbonate rocks. 111. Acetic acid for insoluble residues. Proc. Penn. Acad. Sci., 29: 181-185. GEDROIZ, K., 1922. On the absorptive power of soils. US.,Dept. Conserv. GILBERT, C. M. and TURNER, F. J., 1949. Use of the universal stage in sedimentary petrography. Am. J. Sci., 247: 1-26. GLOVER, E. D., 1961. Methods of solution of calcareous materials using the complexing agent, E.D.T. A. J. Sediment. Petrol., 3 1 : 622-626. GODWIN,F. R. S., 1962. Radiocarbon dating-Fifth International Conference. Nature, 195 (4845): 943-945. GOLDSMITH, J. R., GRAF,D. L. and JOENSUU, 0. I., 1955. The Occurrence of magnesium calcites in nature. Geochim. Cosmochim. Acta, 7: 212-230.
334
K. H. WOLF, A. J. EASTON AND S. WARNE
GOLDSMITH J. R., GRAF,D. L., WITTERS, J. and NORTHROP, D. A., 1962. Studies in the system CaCOs-MgC03-FeC03. J. Geol., 70: 659-688. GOTO,M., 1961. Some mineralogicalchemical problems concerning calcite and aragonite, with special reference to the genesis of aragonite. J. Fac. Sci., Hokkaido Univ., 1: 571440. GRAF,D. L., 1960. Geochemistry of carbonate sediments and sedimentary carbonate rocks. 1V. Isotopic composition. Illinois State Geol. Surv., Circ., 308: 5-23. GRAF,D. L., 1961. Crystallographic tables for the rhombohedra1 carbonates. Am. Mineralogist, 46: 1283-1316.
GRAF,D. L., 1962. Minor element distribution in sedimentary carbonate rocks. Geochim. Cosmochim. Acta, 26: 849-856.
GRAF,D. L. and GOLDSMITH, J. R., 1955. Dolomite-magnesian calcite relations at elevated temperatures and COz pressures. Geuchim. Cosmochim. Acta, 7: 109-128. GRAF,D. L. and GOLDSMITH, J. R., 1963. Carbonate mineralogy. In: Subsurface Geology of Eniwetok Atoll-US., Geol. Surv., Profess. Papers, 260-BB: 1048-1053; 1065-1066. GRASENICK, F. und GEYMEYER, W., 1962. Eine elektron-mikroskopische Methode zur Untersuchung von Kalzit und Aragonit. Radex Rundschau, 1962: 3 3 4 2 . GRAYSON, J. F., 1956. The conversion of calcite to fluorite. Micrupaleontology, 2: 71-78. GREGOIRE, C., 1961. Structure of the conchiolin cases of the prisms in Mytilus edulis L. J. Biophys. Biochem. Cytol., 9: 395400.
GREGOIRE,C., 1962. On submicroscopic structure of the Nautilus shell. Inst. Roy. Sci. Nut. Belg., Bull., 38: 2-56.
GREGOIRE, C. et MONTY,C., 1962. Observations au microscope Clectronique sur le calcaire a pate fine entrant dans le constitution de structures stromatolithiques du VisCen moyen de la Belgique. Ann. SOC.Gdol. Belg., Bull., 85: 389-397. GRIM,R. E., 1953. Clay Mineralogy. McGraw-Hill, New York, N.Y., 500 pp. R. W., HEATON, E. and ROBERTS, A. L., 1945. Constitution of refractory clays. 11. GRIMSHAW, Trans. Brit. Ceram. Soc., 44: 76-92. GROSS,M. G., 1964. Variations in the 180/180 and 13C/12Cratios of diagenetically altered limestones on the Bermuda Islands. J. Geol., 72: 170-194. GROVES, A. W., 1951. Silicate Analysis, 2 ed. Allen and Unwin, London, 336 pp. GRUNAU, H. R., 1959. Mikrofacies iind Schichtung ausgewiihlter, jungmesozoischer, Radiolaritfuhrender Sediment-Serien der Zentral-Alpen. Brill, Leiden, I 79 pp. GRUSS,H., 1958. Exhalativ-sedimentlre Mangankarbonat-Lagerstatten. Neues Jahrb. Mineral., Abhandl., 92: 47-107.
GRUVER, R. M., 1950a. Differential thermal studies of ceramic materials. I. Characteristic heat effects of some carbonates. J. Am. Ceram. Soc., 33: 96-101. GRUVER, R. M., 1950b. Differential thermal analysis studies of ceramic materials. 11. Transition of aragonite to calcite. J. Am. Ceram. Soc., 33: 171-174. HAGN,H., 1955. Facies und Microfauna der Gesteine der Bayerischen Alpen. Brill, Leiden, 79 PP. HAMBLIN, W. K., 1962. X-radiography in the study of structures in homogeneous sediments. J. Sediment. Petrol., 32: 201-210.
HANDIN, J. W., HIGGS,D. V., LEWIS,D. R. and WEYL,P. K., 1957. Effects of gamma radiation on the experimental deformation of calcite and certain rocks. Bull. Geol. Soc. Am., 68: 1203-1224.
HANZAWA, S., 1961. Furies and Micro-organisms of the Paleozoic, Mesozoic and Cenozoic Sediments of Japan and her Adjacent Islands. Brill, Leiden, 420 pp. HARBAUGH, J. W., 1959. Marine bank development in Plattsburg Limestone (Pennsylvanian), Neodesha-Fredonia Area, Kansas. Geol. Surv. Kansas, Bull., 134 (8): 289-331. HARBAUGH, J. W., 1964. Use of factor analysis in recognizing facies boundaries. Am. Assoc. Petrol. Geologists, 48: 529 (abstract). HARBAUGH, J. W. and DEMIRMEN, F., 1964. Application of factor analysis to petrologic variations of Americus Limestone (Lower Permian), Kansas and Oklahoma. Geol. Surv. Kansas, Spec. Distribution Publ., 15: 40 pp. R. I. and TUTTLE,0. F., 1955. Studies in the system CaO-MgO-COZ. Am. J. Sci., HARKER, 253: 274-282.
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
335
HAUL,R. A. W. and HEYSTEK, H., 1952. Differential thermal analysis of the dolomite decomposition. Am. Mineralogist, 37: 166-1 79. HAUN,J. D. and LEROY,L. W. (Editors), 1958. Subsurface Geology in Petroleum Exploration. Colo. School Mines, Golden, Colo., 887 pp. HAY,W. W. and TOWE,K. M., 1962. Electron-microscope studies of Braurudosphaera bigelowi and some related Coccolithophorids. Science, I37 (3528): 426-427. HAYES, J. R., 1958. Miscellaneous petrologic analyses. In: J. D. HAUN and L. W. LEROY(Editors), Subsurface Geology in Petroleurn Exploration. Colo. School Mines, Golden, Colo., pp. 95-1 18. R. M., 1963. Dip determination in carbonate cores. J. Sediment. Petrol., 33: 680-693. HEDBERG, HEEGER, J. E., 1913. Uber die microchemische Untersuchung fein verteilter Carbonate im Gesteinsschliff. Zentr. Mineral., 191 3: 44-5 l . HEEZEN, B. C. and JOHNSON 111, G. L., 1962. A peel technique for unconsolidated sediments. J. Sediment. Petrol., 32: 609-613. HENBEST, L. G., 1931. The use of selective stains in paleontology. J. Paleontol., 5: 355-364. HERZOG,L. F., ALDRICH, L. T., MOLYK,W. K., WHITING, F. B. and AHRENS, L. H., 1953. Variations in strontium isotope abundance in minerals. 11. Radiogenic Y3r in biotite, feldspar and celestite. Trans. Am. Geophys. Union, 34: 461470. HILTROP, C. L. and LEMISH, J., 1960. A method for determining the relative abundance and composition of calcite and dolomite in carbonate rocks. Proc. Iowa Acad. Sci., 67: 237-245. HIRST,D. M. and NICHOLLS, G. D., 1958. Techniques insedimentary geochemistry. 1 . Separation of the detrital and non-detrital fractions of limestones. J. Sediment. Petrol., 28: 468481. HOOPER,K., 1964. Electron probe X-ray microanalysis of Foraminifera: an exploratory study. J. Paleontol., 38: 1082-1092. HOWELL, J. E. and DAWSON,K. R., 1958. Technique for optical determination of iron-bearing dolomites. Can. Mineralogist, 6: 292-294. HOWIE,R. A. and BROADHURST, F. M., 1958. X-ray data for dolomite and ankerite. Am. Mineralogist, 43: 1210-1214. Hsu, K. J., 1967. Chemistry of dolomite formation. In: G. V. CHILINGAR, H. J. BISSELL and R. W. FAIRBRIDGE (Editors), Carbonate Rocks, B. Elsevier, Amsterdam, pp. 169-191. HUEGI,TH., 1945. Gesteinsbildend wichtige Karbonate und deren Nachweis mittels Farbmethoden. Schweiz. Mineral. Petrog. Mitt., 25: 114-140. HUGHES, P. W., BRADLEY, W. F. and GLASS,H. D., 1960. Mineralogical analysis of carbonate rocks by X-ray diffraction. J. Sediment. Petrol., 30: 619-626. HUNT,J. M. and JAMIESON, G. W., 1956. Oil and organic matter in source rocks of petroleum. Bull. Am. Assoc. Petrol. Geologists, 40: 477488. IMBRIE, J. and PURDY,E. G., 1962. Classification of modern Bahamian carbonate sediments. In: W. E. HAM(Editor), Classification of Carbonate Rocks-Am. Assoc. Petrol. Geologists, Mem., 1 : 253-272. IMMBRIE, J., 1964. Statistical approaches to paleoecology. In: J. IMBRIE and N. NEWELL (Editors), Approaches to Paleoecology. Wiley, New York, N.Y., pp.407422. INGERSON, E., 1962. Problems of geochemistry of sedimentary carbonate rocks. Geochim. Cosmochim. Acta, 26: 815-848. IRELAND, H. A., 1950. Curved surface sections for microscopic study of calcareous rocks. Am. Assoc. Petrol. Geologists, 34: 1737-1 739. IVESJR., W., 1955. Evaluation of acid etching of limestones. State Geol. Surv. Kansas, Bull., 114 (1): 1 4 8 . JEFFERY, P. M., COMPSTON, W., GREENHALGH, D. and DE LAETER, J., 1955. On thecarbon-13 abundance of limestones and coals. Geochim. Cosmochim. Acta, 7: 255-286. JODREY, L. H., 1953. Studies on shell formation. 111. Measurement of calcium deposition in shell and calcium turnover in mantle tissue using the mantle-she11 preparation and 45Ca. Biol. Bull., 104:398407. JOHNSON, N. M., 1960. Thermoluminescence in biogenic calcium carbonate. J. Sediment. Petrol., 30: 305-313. JOHNSTON, J. H., 1964. Lower Devonian Algae and encrusting Foraminifera from New South Wales. J. Paleontol., 38: 98-108.
336
K. H. WOLF, A. J. EASTON AND S. WARNE
JURIK,P., 1964. Quantitative insoluble residue procedures. J. Sediment. Petrol., 34: 666-668. KAUFFMAN, A. J. and DILLING, E. D., 1950. Differential thermal curves of certain hydrous and anhydrous minerals, with a description of the apparatus used. Econ. Geol., 45: 222-244. KEITH,M. L., 1962. Isotopic within-shell variation in mollusks, in relation to their environment. Geol. SOC.Am., Spec. Papers, 73 (1962): 185. Abstract. KEITH,M. L. and ANDERSON, G. M., 1963. Radiocarbon dating-fictitious results with mollusk shells. Science, 141 (3581): 634-637. KEITH,M. L. and DEGENS,E. T., 1959. Geochemical indicators of marine and fresh-water sediments. In: P.H. ABELSON (Editor), Researches in Geochemistry, Wiley, New York, N.Y., pp.38-61. KEITH,M. L., ANDERSON, G. M. and EICHLER, R., 1964. Carbon and oxygen isotopic composition of mollusk shells from marine and fresh-water environments. Geochim. Cosmochim. Acta, 28 : 1757-1 786. KENNEDY, G . C., 1947. Charts for correlation of the optical properties with chemical composition of some common rock-forming minerals. Am. Mineralogist, 32: 561-573. KISSINGER, H. E., MCMURDIE, H. F. and SIMPSON, B. S., 1956. Thermal decomposition of manganous and ferrous carbonates. J. Am. Ceram. Soc., 39: 168-172. KITSON,R. R. and MELLON, M. G., 1944. Colorimetric determination of phosphorous as molybdivanado phosphoric acid. Ind. Eng. Chem., Anal. Ed., 16: 379-383. KOBLENCZ, V. and NEMECZ,E., 1953. Huntite from the Dorog Mine, Dorog, Hungary. Foldt. Koz~.,83: 391-395. KUBLER,B., 1958. Calcites magnksiennes d'eau douce dans le Tertiare superieur du Jura Neuchltelois (Canton de Neuchltel), Suisse. Eclogue Geol. Helv., 51 : 676-685. KUDYMOV, B. Y . , 1962. Spectral Well Logging. Elsevier, Amsterdam, 77 pp. KULP,J. L., 1950. Sr isotope age project-progress report. Geol. SOC.Am. Abstr., 61: 1479. KULP,J. L., 1951. Research upon the Sr-isotope method of age determination. Geol. Soc. Am., Interim Proc., 2: 4. KULP,J. L., 1952. The carbon-14 method of age determination. Sci. Monthly, 75: 259-267. KULP,J. L., KENT,P. and KERR,P. F., 1951. Thermal study of the Ca-Mg-Fecarbonate minerals. Am. Mineralogist, 36: 643-670. KULP,J. L., TUREKIAN, K. and BOYD,D. W., 1952. Strontium content of limestones and fossils. Bull. Geol. SOC.Am., 63: 701-716. R. J., 1949. Thermal study of rhodochrosite. Am. KULP, J. L., WRIGHT,H. D. and HOLMES, Mineralogist, 34: 195-219. LAMAR, J. E., 1950. Acid-etching in the study of limestones and dolomites. Illinois State Geol. Surv.. Circ., 156: 1-47. LAMAR, J. E. and THOMPSON, K. B., 1956. Sampling limestone and dolomite deposits for trace and minor elements. Illinois State Geol. Surv., Circ., 221 : 18 pp. LANE,D. W., 1962. Improved acetate peel technique. J. Sediment. Petrol., 32: 870. LANE,N. G., 1958. Environment of deposition of the Grenda Limestone (Lower Permian) in Southern Kansas. Univ. Kansas Publ., State Geol. Surv. Kansas, Bull., 130 (3): 117-164. LEE,P. J., 1963. Correlation of sediments by using an electronic digital computer. Mr. H.H. Ling's 70th Birthday Jubilee volume. Petrol. Geol. Taiwan, 2: 137-147. LEES,A., 1958. Etching technique for use of thin sections of limestones. J. Sediment. Petrol., 28: 2W202. LEITMEIER, H. und FEIGL,F., 1934. Eine einfache Reaction zur Unterscheidung von Calcit und Aragonit. Mineral. Petrog. Mitt., 45: 447-456. LEMBERG, J., 1887. Zur microchemischen Untersuchung von Calcit und Dolomit. Z. Deut. Geol. Ges., 39: 489-492. LEMBERG, J., 1888. Zur microskopischen Untersuchung von Calcite, Dolomit and Predazzit. Z. Deut. Geol. Ges., 40:357-359. LEMBERG, J., 1892. Zur microchemischen Untersuchung einiger Minerale. Z. Deut. Geol. Ges., 44: 224-242. LEWIS,D. R., 1956. The thermoluminescence of dolomite and calcite. J. Phys. Chem., 60: 698-701. LEWIS,D. R., WEYL,P. K., HANDIN, J. W. and HIGGS,D. V., 1956. Effects of plastic deformation
EXAMINATION AND ANALYSIS OF SEDIMENTARY CARBONATES
337
on absorption spectrum and thermoluminescence of calcite. Bull. Am. Phys. Soc., Ser. 2 (1): 87. LIBBY,W. F., 1955. Radiocarbon Dating. University of Chicago Press, Chicago, Ill., 175 pp. N. F., 1952. Mineralogische Untersuchungen an einigen Niederhessischen TertiarLIPPMANN, tonen. Heidelberger Beitr. Mineral. Petrog., 3: 21 9-252. LLOYD,R. M., 1954. A technique for separating clay minerals from limestones. J. Sediment. Petrol., 24: 218-220. LLOYD,R. M., 1964. Variations in the oxygen and carbon isotope ratios of Florida Bay molluska and their environmental significance. J. Geol., 72: 84-1 1 I . LOGVINENKO, N. V., KARPOVA, G. V. and KOSMACHEV, V. G., 1961. The mechanism of isomorphous replacement in carbonates of the calcite group which have a sedimentary origin. Dokl. Akad. Nauk S.S.S.R., Earth Sci. Sect., 138: 657-660. LONGINELLI, A. and TONGIORGI, E., 1964. Oxygen isotopic composition of some right- and leftcoiled Foraminifera. Science, 144 (3621): 1004-1005. LOUPEKINE, I. S., 1947. Graphical derivation of refractive index e for the trigonal carbonates. Am. Mineralogist, 32: 502-507. Low, J. W., 1958. Examination of well cuttings. In: J. D. HAUN and L. W. LEROY(Editors), Subsurface Geology in Petroleum Exploration. Colo. School Mines, Golden, Colo., 17-58. LOWENSTAM, H. A., 1961. Mineralogy, 1 * 0 / l a 0 ratios, and strontium and magnesium contents of recent and fossil brachiopods and their bearing on the history of the oceans. J. Geol., 69: 241-260. LOWENSTAM, H. A. and EPSTEIN, S., 1957. On the origin of sedimentary aragonite needles of the Great Bahama Bank. J. Geol., 65: 364-376. MACKENZIE, R. C. (Editor), 1957. The Differential Thermal Investigation of Clays. Mineral. SOC.(Clay Mineral. Group), London, 456 pp. MANN,V. I., 1955. A spot test for dolomitic limestones. J. Sediment. Petrol., 25: 58-59. MANSON, V. and IMBRIE, J., 1964. Fortran program for factor and vector analysis of geologic data using an I.B.M. 7090 or 7094/1401 computer system. Kansas Geol. Surv. Spec. Disr. Publ., 13: 46 pp. R. G., 1964. Differentiation ofcarbonatesediMAXWELL, W. G. H., JELL,J. S. and MCKELLAR, ments in the Heron Island Reef. J. Sediment. Petrol., 34: 294-308. MCCREA,J. M., 1950. On the isotope chemistry of carbonates and a paleotemperature scale. J. Chem. Phys., 18: 849-857. MCCRONE,A. W., 1963. Quick preparation of peel-prints for sedimentary petrography. J. Sediment. Petrol., 33: 228-230. MCDIARMID, R. A., 1963. The application of thermoluminescence to geothermometry. Econ. Geol., 58: 1218-1228. MCIVER,R. D., 1962. Ultrasonics-a rapid technique for removing soluble organic matter from sediments. Geochim. Cosrnochim. Acta, 26: 343-345. MENNING, J. J. et VITTIMBERGA, P., 1962. Application des Mkthodes Pktrographiques ri l’gtude du Palkozoique Ancien du Fezzan. Comp. FranG. Petroles, Paris, 63 pp. MEYER, R. and TAYLOR, D. W., 1963. Radiocarbon activity of shells from living clams and snails. Science, 141 (3581): 637. MOORE,L. E., 1957. Thermoluminescence of sodium sulfate and lead sulfate, and miscellaneous sulfates, carbonates and oxides. J. Phys. Chem., 61 : 636639. MOORHOUSE, W. W., 1959. The Study of Rocks in Thin-sections.Harper and Row, New York, N.Y., 514 pp. MULLER,G., 1964. Methoden der Sediment-Untersuchung. Schweizerbart, Stuttgart, 303 pp. J. C., 1959. C14-Altersbestimmungvon Siisswasser-Kalkablagerungen. MUNNICH,K. 0.und VOGEL, Naturwissenschaften, 46: 1-3. MURRAY, J. A., FISHER, H. C. and SHADE,R. W., 1951. M. I. T. Fellowship Report. Proc. Nut. Lime Assoc., 49: 95-1 16. NATIONAL BUREAU OF STANDARDS METHODS, 1928.Dolomite N0.88. U S . Dept. Comm., Washington, D.C. Y. R., in press. Carbonate deposits and paieoclimatic implications in the Northeast NAYUDU, Pacific Ocean. Science.
338
K. H. WOLF, A. J. EASTON AND S. WARNE
NORTH,F. J., 1930. Limestones. Van Nostrand, New York, N.Y., 467 pp. OCKERMAN, J. B. and DANIELS, F., 1954. Alpha-radioactivity of some rocks and common materials. J. Phys. Chem., 58: 926. OSTLUND, H. G., BOWMAN, A. L. and RUSNAK, G. A., 1962. Miami natural radiocarbon measurements. 1. Radiocarbon, 4: 51-56. OSTROM, M. E., 1961. Separation of clay minerals from carbonate rocks by using acid. J. Sediment. Petrol., 31: 123-129. PAPAILHAU, J., 1958. Nouveau dispositif d’analyse thermique diffkrentielle. Bull. Soc. Franc. MinPral. Crist., 81: 142-147. PAPAILHAU, J., 1959. Appareil d’analyses thermiques ponderales et diffkrentielles simultankes. Bull. Soc. Franc. MinPral. Crist., 82: 367-373. PARKSJR., J. M., 1953. Use of thermoluminescence of limestones in subsurface stratigraphy. Bull. Am. Assoc. Petrol. Geologists, 37: 125-142. PATTON,J. and REEDER, W., 1956. New indicator for titration of calcium with E.D.T.A. Anal. Chem., 28: 1026-1028. PERCIVAL, S. F., GLOVER, E. D. and GIBSON,L. B., 1963. Carbonate rocks: cleaning with suspensions of hydrogen-ion exchange resin. Science, 142: 1456-1457. PETERSON, M. N. A., 1961. Expandable chloritic clay minerals from upper Mississippian carbonate rocks of the Cumberland Plateau in Tennessee. Am. Mineralogist, 46: 1245-1269. PETERSON, M. N. A., BIEN,G. S. and BERNER, R. A., 1963. Radiocarbon studies of recent dolomite from Deep Spring Lake, California. J. Geophys. Res., 68: 6493-6505. PITRAT,C. W., 1956. Thermoluminescence of limestones of Mississippian Madison Group in Montana and Utah. Bull. Am. Assoc. Petrol. Geologists, 40: 942-952. RAMSDEN, R. M., 1954. A colour test for distinguishing limestone and dolomite. J. Sediment. Petrol., 24: 282. RANKAMA, K., 1956. Isotope Geology. Pergamon, New York, N.Y., 535 pp. RAY,S., GAULT,H. R. and DODD,C. G., 1957. The separation of clay minerals from carbonate rocks. Am. Mineralogist, 42: 681485. REY,M. et NOUET,G., 1958. Microfacies de la R g i on PrPrifaine et de la Moyenne Moulouya. Brill, Leiden, 41 pp. REVELLE, R. and FAIRBRIDGE, R., 1957. Carbonates and carbon dioxide. In: Treatise on Marine Ecology and Paleoecology. I-Geol. Soc. Am., Mem., 61: 239-296. RIEKE,J. K., 1957. Thermoluminescence of miscellaneous inorganic crystals. J. Phys. Chem., 61: 633-636. RILEY, J. P. and WILLIAMS, H. P., 1959a. The microanalysis of silicates and carbonate minerals. 1. Determination of ferrous iron. Mikrochim. Acta, 4: 516-524. RILEY,J. P. and WILLIAMS, H. P., 1959b. The microanalysis of silicates and carbonate minerals. 4. Determination of aluminum in the presence of interfering elements. Mikrochim. Acta, 6: 826-830. RIOULT, M. and RIBY,R., 1963. Examen radiographique de quelques minkrais de fer de I’Ordovicien normand. Importance des rayons X en sedimentologie. Bull. Soc. GPoI. France, 7 (5): 59-61. RITCHIE, A. S., 1964. Chromatography in Geology. Elsevier, Amsterdam, 185 pp. ROBBINS, C. R. and KELLER, W. E., 1952. Clay and other noncarbonate minerals in some limestones. J. Sediment. Petrol., 22: 146-152. RODGERS, J., 1940. Distinction between calcite and dolomite on polished surfaces. Am. J. Sci., 238: 788-798. ROSENBERG, P. E., 1963. Synthetic solid solutions in the systems MgC03-FeC03 and MnC03FeCO3. Am. Mineralogist, 48: 1396-1400. Ross, C. A. and OANA,S., 1961. Late Pennsylvanian and Early Permian limestone petrology and carbon isotope distribution, Glass Mountains, Texas. J. Sediment. Petrol., 31 : 231-244. Ross, C. S., 1935. Origin of the copper deposits of the Ducktown in the Southern Appalachian region. US.,Geol. Surv., Profess. Papers, 179: 8. ROSTOKER, D. and CORNISH, R., 1964. Use of the electron microscope in micropaleontological studies. J. Paleontol., 38: 423-425. ROWLAND, R. A. and JONAS,E. C., 1949. Variations in differential thermal analysis curves of siderite. Am. Mineralogist., 34: 550-555.
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
339
ROWLAND, R. A. and LEWIS,D. R., 1951. Furnace atmosphere control in differential thermal analysis. Am. Mineralogist, 36: 80-91. RUBIN,M., LIKINS,R. C. and BERRY, E. G., 1963. On the validity of radiocarbon dates from snail shells. J. Geol., 71: 84-89. RUOTSALA, A. P., 1964. Determination of calcite/dolomite ratios by infrared spectroscopy. J . Sediment. Petrol., 34: 676-677. SABINS, F. F., 1962. Grains of detrital, secondary, and primary dolomite from Cretaceous of the Western Interior. Bull. Geol. Soc. Am., 73: 1183-1 196. SACAL,V., 1963. Microfacies du Paliozoique Saharien. Comp. Franc. Pktroles, Paris, 30 pp. D. F., 1953. Thermoluminescence and subsurface correlation of limestones. Bull. Am. SAUNDERS, Assoc. Petrol. Geologists, 37: 114-124. SCHWARTZ, F., 1927. Eine Unterscheidung von Siderit und Ankerite durch Anfarben. Z . Prakt. Geol., 37: 190-191. SCHWOB, Y., 1950. Les carbonates rhombokdriques simples et complexes de calcium, magnksium et fer (contribution A I’ktude de leur dissociation thermique). Publ. Tech. Centre Etudes Rech. Ind. Liants Hydrauliques (Paris), 22: 105 pp. SCHUMANN, H., 1948. Die mikroskopische Unterscheidung von Mineralien der Karbonat-Gruppe. Heidelberger Beitr. Mineral. Petrog., 1 : 381-393. SHOJI,R. and FOLK,R. L., 1964. Surface morphology of some limestone types as revealed by electron microscope. J. Sediment. Petrol., 34: 144-155. SHORT,N. M., 1962. Ste. Genevieve (Mississippian) Formation at its type locality in Missouri. Bull. Am. Assoc. Petrol. Geologists, 46: 1912-1934. SIEGEL,F. R., 1963. Artificially induced thermoluminescence of sedimentary dolomites. J. Sediment. Petrol., 33: 64-72. SKINNER, H. C. W., 1963. Precipitation of calcian dolomites and magnesian calcites in the Southeast of South Australia. Am. J. Sci., 261: 449472. SKINNER, H. C. W., SKINNER, B. J. and RUBIN,M., 1963. Age and accumulation rate of dolomitebearing carbonate sediments in South Australia. Science, 139: 335-336. SLOSS, L. L., 1948. Sequence in Layered Rocks. McGraw-Hill, New York, N.Y., 507 pp. SLOSS,L. L. and COOKE,S. R. B., 1946. Spectrochemical sample logging of limestones. Bull. Am. Assoc. Petrol. Geologists, 30: 1888-1898. SMYKATZ-KLOSS, W., 1964. Differential-Thermo-Analysen von einigen Karbonat-Mineralen. Beitr. Mineral. Petrog., 9: 481-502. STAUFFER, K. W., 1962. Quantitative petrographic study of Paleozoic carbonate rocks, Caballo Mountains, New Mexico. J. Sediment. Petrol., 32: 357-396. STERNBERG, R. M. and BELDING, H. F., 1942. Dry-peel technique. J. Paleontol., 16: 135-136. STEVENS, R. E. and CARRON, M. K., 1948. Simple field test for distinguishing minerals by abrasion pH. Am. Mineralogist, 33: 3149. STRAKHOV, N. M., 1957. Mkthodes d’budes des Roches S6dimentaires. Bur. Rech. Gkol., Gkophys. Minkral., Paris, I : 541 pp.; 2: 535 pp. STUIVER, M., 1964. Carbon isotope distribution and correlated chronology of Searles Lake sediments. Am. J. Sci., 262: 377-392. TAFT,W. H. and HARBAUGH, J. W., 1964. Modern Carbonate Sediments of Southern Florida, Bahamas, and Espiritu Santo Island, Baja California; A Comparison of Their Mineralogy and Chemistry-Stanford Univ. Publ., Univ. Ser., Geol. Sci., 8 (1964): 133 pp. TAT~UMOTO, M. and GOLDBERG, E. D., 1959. Some aspects of the marine geochemistry of uranium. Geochim. Cosmochim. Acta, 17: 201-208. TENNANT, C. B. and BERGER,R. W., 1957. X-ray determination of dolomite/calcite ratio of a carbonate rock. Am. Mineralogist, 42: 23-29. TERRY,R. D. and CHILINGAR, G. V., 1955. Summary of “Concerning some additional aids in studying sedimentary formations” by M.S. Shvetsov. J. Sediment. Petrol., 25 (3): 229-234.
THUGETT, ST. J., 1910. Ueber chromatische Reaktion auf Calcit und Aragonit. Zentr. Mineral. Geol. Palaontol., 786-790. THURBER, D., BROECKER, W. and KAUFMAN, A., 1963. 234U-230Th method of age determination and its application to marine carbonates. Geol. Soc. Am., Progr. Am. Meeting, 1963: 166A.
340
K . H. WOLF, A. J . EASTON AND S. WARNE
T R ~ E W. R , E., 1959. Optische Bestimmung der Gesteinsbildenden Minerale. Schweizerbart, Stuttgart, 147 pp. H. A., EPSTEIN,S. and MCKINNEY, C. R., 1951. Measurement of UREY,H. C., LOWENSTAM, paleotemperatures and temperatures of the Upper Cretaceous of England, Denmark, and the southeastern United States. Bull. Geol. SOC.Am., 62: 399416. USDOWSKI, H. E., 1963. Die Genese der Tutenmergel oder Nagelkalke (cone-in-cone). Beitr. Mineral. Petrog., 9: 95-1 10. VANDER WALT,C. F. J. and VAN DER MERWE,A.J.,1938.Colorimetricdetermination ofchromium in plant ash, soil, water and rocks. Analyst, 63: 809-81 1. VOGEL,A. I., 1951. Quantitative Inorganic Analysis, 2 ed. Longmans, London, 918 pp. VOGEL,J. C., 1959. Ueber den Isotopengehalt des Kohlenstoffs in Siisswasser-Kalkablagerungen. Geochim. Cosmochim. Acta, 16: 236-242. WAITE,J. M., 1963. Measurement of small changes in lattice spacing. Applied to calcites of Pennsylvanian age limestone. Am. Mineralogist, 48: 1033-1039. WALGER, E., 1961. Zur mikroskopischen Bestimmungder Gesteinsbildenden Karbonate im Diinnschliff. Neues Jahrb. Mineral., Monatsh., 8: 182-187. WARNE,S., 1961. L'analyse thermique differentielle de la sidtrite. Bull. SOC.Franc. MinPral. Crist., 84: 234-237. WARNE,S., 1962a. Determination of COZ in carbonate rocks by controlled loss on ignitionadditions and modifications. J. Sediment. Petrol., 32: 877-881. WARNE,S., 1962b. A quick field or laboratory staining scheme for the differentiation of the major carbonate minerals. J. Sediment. Petrol., 32: 29-38. WARNE,S., 1963. The Nature and Significance of Microscopic Mineral Matter in some New South Wales Coals.Thesis, Univ. New S. Wales, Sydney, N.S.W., 306 pp. Unpublished. WARNE,S., 1964. The identification and evaluation of minerals in coal by differential thermal analysis. Proc. Symp. Inorg. Constitution Fuel, Melbourne, pp.235-246; 19.1-19.6. WARNE,S. and BAYLISS,P., 1962. The differential thermal analysis of cerussite. Am. Mineralogist, 47: 1011-1023. WATABE, N. and WILBUR,K. M., 1961. Studies on shell formation. 9. An electron microscope study of crystal layer formation in the oyster. J. Biophys. Biochem. Cytol., 9: 761-772. WATABE, N., SHARP,D. G. and WILBUR,K. M., 1958. Studies on shell formation. 8. Electron microscopy of crystal growth of the nacreous layer of the oyster Crassostrea virginica. J. Biophys. Biochem. Cytol., 4: 281-286. WAYLAND, R. G., 1942. Composition, specific gravity and refractive indices of rhodochrosite; rhodochrosite from Butte, Montana. Am. Mineralogist, 27: 614-628. WEBB,T. L. and HEYSTEK, H., 1957. The carbonate minerals. In: R. C. MACKENZIE (Editor), The Differential Thermal Analysis of Clays. Mineral. SOC.(Clay Mineral. Group), London, pp.329-363. WEBER,J. N., 1964a. Carbon and oxygen isotope ratios as environmental indicators: anomalous results from carbonate shells from beach sediments of Lake Managua, Nicaragua. Nature, 202 (4914): 63. WEBER, J. N., 1964b. Trace element composition of dolostones and dolomites and its bearing on the dolomite problem. Geochim. Cosmochim. Acta, 28: 1817-1 868. WEBER,J. N., 1964c. Variations of 180/160 and 13C/12Cin the calcium carbonate of Pleistocene varved clays from Toronto, Canada. Nature, 202 (4934): 791-792. WEBER,J. N. and KEITH,M. L., 1962. Isotopic composition and environmental classification of selected limestones and fossils. Geol. SOC.Am., Spec. Papers, 73 (1962): 259. Abstract. J. N. and LA ROCQUE, A., 1963. Isotope ratios in marine mollusk shells after prolonged WEBER, contact with flowing fresh water. Science, 142: 1666. WEBER,J. N. and SMITH,F. G., 1961. Rapid determination of calcite/dolomite ratios in sedimentary rocks. J. Sediment. Petrol., 31: 130-132. WEBER, J. N., WILLIAMS, E. G. and KEITH,M. L., 1964. Paleoenvironmental significance of carbon isotopic composition of siderite nodules in some shales of Pennsylvanian age. J. Sediment. Petrol., 34: 814-818. WICKMAN, F. E., 1948. Isotope ratios: a clue to the age of certain marine sediments. J. Geol., 56: 6146.
EXAMINATION A N D ANALYSIS OF SEDIMENTARY CARBONATES
34 1
WICKMAN, F. E. and VON UBISCH,H., 1951. Two notes on the isotopic constitution of carbon in minerals. Geochim. Cosmochim. Acta, I : 119-122. WICKMAN, F. E., BLIX,R. and VONUBISCH,H., 1951. On the variations in the relative abundance of the carbon isotopes in carbonate minerals. J. Geol., 59: 142-150. WILBUR, K. M. and JODREY, L. H., 1952. Studies on shell formation. 1. Measurement of the rate of shell formation using 45Ca. Biol. Bull., 103: 269-276. WILLARD, H. H. and GREATHOUSE, L. H., 1917. The colorimetric determination of manganese by oxidation with periodate. J. Am. Chem. SOC.,39: 2366-2377. WILLIAMS, M. and BARGHOORN, E. S., 1963. Biochemical aspects of the formation of marine carbonates. In: I. A. BREGER (Editor), Organic Geochemistry. Pergamon, New York, N.Y., pp.596-604. WINCHELL, A. N., 1951. Elements of Optical Mineralogy. Wiley, New York, N.Y., 551 pp. WINCHELL, A. N. and MEEK,W. B., 1947. Birefringence/dispersion ratio as a diagnostic. Am. Mineralogist, 32: 336-343. WOLF, K. H., 1963a. Syngenetic to Epigenetic Processes, Paleoecology, and Classification of Limestones; in Particular Reference to Devonian Limestones of Central New South Wales. Thesis, Univ. Sydney, Sydney, 21 1 pp. Unpublished. WOLF,K. H., 1963b. Limestones-Summary Report. Australian Natl. Univ., Canberra, A.C.T., 251 pp. Unpublished. WOLF,K. H., 1965a. Petrogenesis and paleoenvironment of Devonian algal limestones of New South Wales. Sedimentology, 4 (1 /2): 1 13-1 77. WOLF,K. H., 1965b. “Grain-diminution” of algal colonies to micrite. J. Sediment. Petrol., 35: 420-427. WOLF,K. H., 196%. Gradational sedimentary products of calcareous Algae. Sedimentology, 5 : 1-37. WOLF,K. H., CHILINGAR, G. V. and BEALES, F. W., 1967. Elemental composition of carbonate skeletons, minerals, and sediments. In: G. V. CHILINGAR, H. J. BISSELL and R. W. FAIRBRIDGE (Editors), Carbonate Rocks, B, Elsevier, Amsterdam, pp.23-149. WOLF,K. H. and CONOLLY, J., 1965. Petrogenesis and paleoenvironment of limestone lenses in Upper Devonian red-beds of New South Wales. Paleogeography, Paleoclimatol., Paleoecol., l(1): 69-111. WRAY,J. L., 1957. Factors in age determination of carbonate sediments by thermoluminescence. Bull. Am. Assoc. Petrol. Geologists, 41: 121-129. WRAY,J. L. and DANIELS, F., 1957. Precipitation of calcite and aragonite. J. Am. Chem. Sor., 79: 2031-2034. YOE,J. H. and ARMSTRONG, A. R., 1947. Colorimetric determination of titanium with disodium-1, 2-dihydroxybenzene-3, 5-disulphonate. Anal. Chem., 19: 100-102. ZELLER, E. J., 1954. Thermoluminescence of carbonate sediments. In: H. FAUL (Editor), Nuclear Geology. Wiley, New York, N.Y., 414 pp. ZELLER, E. J. and PEARN, W. C., 1960. Determination of past Antarctic climate by thermoluminescence of rocks. Trans. Am. Geophys. Union,41 : 118. ZELLER, E. J. and WRAY,J. L., 1956. Factors influencing the precipitation of calcium carbonate. Bull. Am. Assoc. Petrol. Geologists, 40: 140-152. ZELLER, E. J., WRAY,J. L. and DANIELS, F., 1955. Thermoluminescence induced by pressure and crystallization. J. Chem. Phys., 23:2187. ZELLER, E. J., WRAY,J. L. and DANIELS, F., 1957. Factors in age determination of carbonate sediments by thermoluminescence. Bull. Am. Assoc. Petrol. Geologists, 41 : 121-129. ZEN, E-AN, 1956. Correlation of chemical composition and physical properties of dolomite. Am. J. Sci., 254: 51-60. ZUMPE,H. M., 1964. The detection of phosphatization in calcareous sediments- a fluorescence method. J. Sediment. Petrol., 34: 691-692.
Chapter 9
PROPERTIES AND USES OF THE CARBONATES FREDERIC R. SIEGEL
Department of Geology, The George Washington University, Washington, D.C. (U.S.A.)
SUMMARY
Carbonate rocks are raw materials indispensable to industrial development. In recent years, limestone, dolomite, and marble constituted more than 70% of all rocks quarried in the United States. Statistics on production and dollar value for 1961, 1962, and 1963 are presented, by uses. The uses to which carbonate rocks and minerals can be put is a function of their physical and/or chemical properties. This chapter contains listings of selected chemical analyses and important physical properties of carbonate rocks. More than one hundred uses for carbonate rocks and minerals are given together with the users’ general chemical and physical requirements. Because of space limitations, only three of the many areas of active research on carbonate properties are discussed: solid solution and subsolidus relations, thermoluminescence, and infrared absorption.
SOME ASPECTS AND STATISTICS OF CARBONATE ECONOMICS
A myriad of uses exist for carbonate minerals and rocks or products derived from them. Indeed, industrial development in the United States and other areas of the world is often reflected in the number of tons of carbonate raw material produced and sold each year. If, for example, there were a cut-back in steel production or a lag in building construction, there would generally be a concomitant drop-off in the quarrying of carbonate rock. Similarly, a reduction in funds for state and federal highway development programs would cause a great drop in carbonate quarrying. During 1962, more than 70% of all rock quarried in the United States was limestone, dolomite, and marble. Crushed and broken stone comprised a major part of the carbonate rock production, and 93 % of almost 500 million short tons (representing about U.S.$ 600 million) was used for concrete and road stone, cement (Portland and natural), flux, agriculture, and lime and dead-burned dolomite. In Table I there is a categorization of statistics on production and dollar value ~-
l
Former address: The University of Kansas, State Geological Survey, Lawrence, Kans. (U.S.A.).
TABLE I CARBONATE ROCKS SOLD OR USED BY PRODUCERS IN THE UNITED STATES, BY USES] ~
1961 Quantity (x 1,000 short tons)
-
Value (x US.$ 1,000)
1962
Quantity ( x 1,ooo short tons)
1963
Value (x US.$ 1,m)
-
Quantity ( x 1,m short tons)
Value (x
US.$
1,000) ~~
Limestone and dolomite (crushed and broken stone) concrete and roadstone 258,997 flu 27,198 agriculture 22,196 railroad ballast 4,260 riprap 9,138 alkali manufacture 2,560 calcium-carbide manufacture 764 cement (Portland and natural) 79,779 coal-mine dusting 372 fill material 266 filler (not whiting substitute): asphalt 2,130 fertilizer 438 other 219 filtration 148 glass manufacture 1,211 lime and dead-burned dolomite 18,124 limestone sand 1,693 limestone whiting3 802 mineral food 695 paper manufacture 400 poultry grit I53
338,798 39,725 38,478 5,376 10,440 2,878 785 85,883 1,527 277
276,878 26,081 23,029 5,065 10,016 2,840
365,098 36,821 39,348 6,578 12,253 3,188
292,976 27,185 25,956 4,923 10,690 2,955
380,893 39,322 44,195 6,4 10 13,229 3,282
83,318 400 440
92,886 1,667 330
86,842 539 383
92,646 2,268 296
5,408 1,080 873 22 1 3,736 28,283 2,596 9,242 3,723 1,129 1,185
3.208 448 35 1 79 1,337 19,356 1,706 838 692 27 1 161
6,955 1,132 1,567 141 4,294 32,959 3,103 9,639 3,847 82I 1,333
1,994 457 419 62 1,492 21,450 1,759 785 618 358 160
5,012 1,133 1,921 117 4,781 36,024 3,234 9,298 3,793 1,099 1,342
*2
*2
*2
*2
w
refractory (dolomite) suger refining other uses4 uses unspecified subtotal
235 882 2,838 1,900
465 2,215 4,603 2,475
322 623 1,741 1,753
563 1,506 4,253 2,518
769 646 2,125 2,805
1,297 1,580 5,472 3,282
437,398
591,401
460,953
632,800
488,348
661,926
Marble (crushed and broken stone) terazzo other uses5
397 1,038
4,535 7,859
3 80 1,243
4,866 9,512
367 1,385
4,768 8,797
subtotal
1,435
12,394
1,673
14,378
1,752
13,565
ga 0
8w
-
i* 2: U
8 e i2
* c1
0
2
Limestone (dimension stone) building rough: construction architectural dressed: sawed and cut rubble curbing and flagging
61 223 330 219 22
323 3,455 12,066 725 169
82 197 318 284 15
326 3,000 12,476 928 117
52 196 347 282 18
subtotal
855
16,738
896
16,847
895
18,134
Marble (dimension stone) buildings rough; architectural dressed: sawed and cut monumental: rough and finished
37 106 14
1,168 14,670 2,728
34 95 17
1,330 14,269 3,140
28 80 42
1,334 12,574 7,294
subtotal
157
18,566
146
18,739
150
2 1,002
4
v1
289 3,091 13,498 1,104 152 ~
.~
w
R
TABLE I (continued) 1961 Quantity ( x 1,000 short tons)
1963
1962 Value ( x U.S.$ 1,000)
Quantity
short tons)
1,000)
.rhort tons)
Value ( x U.S.b 1,000)
(x
1,OOo
Value ( x U.S.%
Quantity ( x 1,000
~
Shell concrete and road material cement lime poultry grit mineral food other uses7
subtotal Calcareous marl agriculture cement
subtotal grand total
4,406 1,420 598 3 78
18,256 4,881 1,782 5,004 14 438
12,792 5,117 1,441 581 4 113
18,611 5,531 1,876 4,635 22 566
11,821 5,278 1,169 552
17,277 5,847 1,663 3,874
I99
759
18,004
30,375
20,054
31,241
19,019
29,420
223 876
168 819
226 956
156 855
260 904
178 811
1,099
987
1,182
1,Ol I
1,164
989
458,948
670,461
485,042
715,016
511,328
745,036
1 1,499
*2
*2
Data for 1961 and 1962were given by ANONYMOUS (1963), those for 1963by ANONYMOUS (1964a). Included with “other uses”. 3 Includes stone for filler, abrasives, calcimine, calking compounds, ceramics, chewing gum, fabrics, floor coverings, insecticides, leather good, paint, paper, phonographic records, plastics, pottery, putty, roofing, rubber, Wire coating, and unspecified uses. Excludes limestone whiting made by companies from purchased stone. 4 Includes stone for acid neutralization, calcium carbide (1962), cast stone, chemicals (unspecified), concrete products, disinfectant and animal sanitation, electrical products, magnesia, magnesite, magnesium, mineral wool, oil-well drilling, patching plaster, rice milling, road base, roofing granules, stucco, terrazo, and water treatment. Stone for agriculture, asphalt filler, flux, poultry grit, roofing, stone sand, stucco, whiting and unspecified uses. 1961: US.$ 8,934,000 for exterior use, U.S.$ 6,904,000 for interior use; 1962: US.$ 9,575,000 for exterior use; U.S.$ 6,024,000 for interior use; 1963: US.$ 7,351,000 for exterior use; U.S. $ 6,357,000 for interior use.
’Agriculture, asphalt filler to whiting.
347
PROPERTIES A N D USES OF THE CARBONATES
TABLE I1 CEMENT PRODUCTION OF SELECTED COUNTRIES WHICH ACCOUNT FOR ABOUT WORLD PUODUCTlON
90%
OF THE TOTAL
(After ANONYMOUS, 1964c) 1961
Country
Argentina Austria Australia Brazil Belgium Canada China Czechoslovakia Denmark Egypt France Germany (eastern) Germany (western) India Italy Japan Korea (North) Mexico Pakistan Poland Roumania South Africa Spain Sweden Switzerland Turkey U.S.S.R. United Kingdom United States Yugoslavia World total
* Estimate made by the U.S.
I962
(long tons)
(long tons)
2,856,900 3,035,450 2,813,000 4,636,341 4,678,792 5,541,025 9,800,000* 5,259,000 2,879,140 2,107,000 15,138,469 5,192,000 26,714,000 8,114,000 17,698,986 24,243,000 2,226,000 2,987,149 1,223,000 7,248,000 3,255,538 2,557,420 6,408,005 2,964,000 3,544,292 1,995,971 50,194,000 14,149,000 56,841,100 2,299,000 33I ,000,000
2,857,000 3,008,830 2,887,000 4,992,000 4,817,296 6,059,133 8,900,000* 5,620,000 2,937,900 2,260,000 16,433,000 5,346,000 28,141,000 8,450,000 19,838,415 28,33 1,000 2,338,000 3,299,000 1,373,000 7,422,000 3,434,129 2,616,870 6,342,000 3,006,000 3,667,018 2,279,961 56,394,000 14,030,000 59,074,300 2,478,000 353,000,000
Bureau of Mines.
for most of the carbonate rock sold or used by producers in the United States in 1961, 1962, and 1963, by uses. No such detailed data are available on a worldwide basis. Cement production figures, however, have been published and are presented in Table 11. They show that in 1962, 30 countries accounted for about 90% of the world production of 353 million long tons of cement. During 1962, seven countries (China, France, Germany, Japan, the United Kingdom, the U.S.S.R., and the United States) produced over 75 % of the world total of 618 mil-
348
F. R. SIEGEL
lion long tons of steel ingots and castings, pig iron, and ferro-alloys. Ifone can extrapolate from this to the amount of carbonate rocks (or derivatives) used in the siderurgical industry, an extremely conservative estimate would be well over 1,000 million long tons. In addition to their direct and indirect applications in many industrial processes, limestones and dolomites are reservoir rocks for more than one-half of the known petroleum reserves of the world (IMBT, 1950), and act as host rock for numerous important metalliferous ore deposits. Equally impressive is the fact that in many areas, the major source of water is from limestone aquifers. Although the practical (economic) value of the carbonates is emphasized in the later paragraphs of this chapter, one must not forget their meaning to the academician. In his study of fossils and other features commonly associated with the carbonate rocks, the geoscientist can often find clues for solving economic problems by delving into the geologic past, reconstructing environments that existed at the time of their formation, developing fundamental concepts, and establishing parameters which could show trends important to successful exploitation.
PROPERTIES
Introduction
The physical, chemical, optical, and other properties of carbonate rocks influence (within certain limits) their economic potential, that is, the maximum number of uses they might serve. Because these properties are in great part determined by those of the carbonate mineral(s) in the rock and because the carbonate minerals themselves can be very valuable, selected physical, optical, and crystallographic properties of the economically important carbonate minerals are presented here (Tables 111-V). These properties can be significantly altered by cationic substitution, especially in calcite and dolomite. In fact, much recent research has been devoted to the solid solution and subsolidus relations within the calcite group minerals. This aspect is discussed in another part of the chapter. Physical proper ties
Factors which most affect carbonate economics are the physical properties of the quarried material. For example, to be suitable for building stone, limestone, dolomite, or marble must be strong, durable, and reasonably workable; in addition, stone which has these qualities and is aesthetically pleasant to view, will have greater dollar value. Basic properties are given in Table VI. These are generally sufficient for the builders’ (architectural and engineering) needs, but there are many other physical
w
TABLE 111
E
PHYSICAL PROPERTIES OF SOME ECONOMICALLY IMPORTANT CARBONATE MINERALS
i+?i
(After LANGE,1956;DANA, 1959;KRAUSet al., 1959;and DEER et al., 1962) Mineral
Chemical formula Hardness (pure)
Specific gravity
Colour
Common impurities
Cleavage
colourless or white
Mn, Fe, Mg for Ca
(1011)perfect
pink, white, or colourless
Fe, Mn, Co, Zn for Mg, Pb for Ca Fe, Ca, Mn for Mg Fe, Ca, Mg, Zn for Mn Mn, Mg, Ca for Fe Fe, Mn, Ca, Mg, Cd, Cu, Co, Pb for Zn Sr, Pb,Zn for Ca
(1011)perfect
Sr, Ca for Ba
(010)and (110)
Ca for Sr
(1 10) good (1 10) good and
calcite
caco3
dolomite
CaMg(CO3)n
3 on (1011) 2.72 2.5 on base 2.85 3.54
magnesite rhodochrosite siderite smithsonite
MgC03 MnCOs FeCO3 ZnCOa
3.5-5 3.54 3.54 4-4.5
3.0-3.2 3.5-3.7 3.96 4.3M.45
white, gray, yellow, or brown rose-red or light pink brown brown or green
aragonite
CaC03
3.54
2.95
witherite
BaC03
3.5
4.3
colourless, white, or pale yellow colourless, white, or gray
strontianite cerussite
SrC03 PbC03
3.54 3-3.5
3.7 6.55
white, gray, yellow, or green colourless, white, or gray
malachite azurite
CuzCOa(0H)z 3.54 Cu3(OH)z(C03)2 3.54
3.9403 3.77
bright green intense azure blue
(1011)perfect (1011) perfect
(lOT1) perfect (1011)perfect (010) and (110)
imperfect
poor
(021)fair
(001) perfect
(021)imperfect
TABLE I V w
OPTICAL DATA ON THE ECONOMICALLY IMPORTANT CARBONATE MINERALS
VI
0
(After LARSENand BERMAN, 1934; WINCHELL and WINCHELL, 1951; MOOREHOUSE, 1959; and DEER et al., 1962) 2V
Dispersion
Colour in section
0.172-0.190
-
very high
co1our1ess
0.181-0.196
-
high
colourless
0.191-0.219
-
very high
colourless
0.220-0.221
-
high
0.207-0.242
-
high
0.228-0.225
-
high
co1our1ess to pink colourless to brown colourless
0.155
18-18.5'
low
colourless
0.148
16"
very low
colourless
0.1 50-0.149
7-10"
low
colourless
0.273-0.214
8-8.5"
high
colourless
0.254
43
high
green
0.108
68
low
blue
Mineral
System
Optic sign
Indices of refraction
Birefringence
calcite
hexagonal
uniaxial
dolomite
hexagonal
uniaxial
magnesite
hexagonal
uniaxial
rhodochrosite
hexagonal
uniaxial
siderite
hexagonal
uniaxial
smithsonite
hexagonal
uniaxial
ne=1.486-1.550 no=1.658-1.740 ne= 1.5W1.520 no = 1.681-1.716 ne=1.509-1.563 no=1.700-1.782 ne=1.597-1.605 no= 1.817-1.826 ne=1.575-1.633 no=1.782-1.875 ne= 1.621-1.625 no= 1.849-1.850 nz= 1.53G1.531 nu=1.680-1.682 nz= 1.685-1.686 nz =1.529 nu=1.676 nz=1.677 nz =1.516-1 520 nv= 1.664-1.667 nc= 1.666-1.669 nz=1.803-1.804 nu=2.0742.076 nz =2.076-2.078 nz =1.655 nu=1.875 n2=1.909 nz= 1.730 nu= 1.758 n2=1.838
(-1
(-1
(3
(-1
(-1
(-)
aragonite
orthorhombic
biaxial
witherite
orthorhombic
biaxial
orthorhombic
biaxial
strontianite
(-1
(-1
(-)
4
cerussite
orthorhombic
biaxial
malachite
monoclinic
biaxial
azurite
monoclinic
biaxial
(-1
(4
(+I
Optic axial plane
O
PROPERTIES AND USES OF THE CARBONATES
35 1
properties which have been measured and reported, and which must be known before a carbonate rock may be considered for a specializeduse. A classic compilation of quantities important for the physics and physical chemistry of geological materials was published by BIRCHet al. (1942) in the Handbook of Physical Constants. Selected data from this publication are presented in Tables VII-XIX. Methods of testing rock materials for several of their physical properties have been fairly well standardized by the American Society for Testing and Materials (A.S.T.M.). Many of these tests, however, were not directly applicable to samples obtained, for example, by diamond drilling techniques. Therefore, in a program designed to determine the petrographic and physical properties of mine rock and establish correlations between these properties and the costs of various mining operations, U.S. Bureau of Mines scientists began by developing or adapting methods for measuring the physical properties of rock from core specimens obtained by diamond drilling (OBERTet al., 1946). The standardization of testing methods was necessary first to demonstrate that the size of the sample or the testing conditions did not affect the results; second, to establish a correlation factor so that values obtained, which were influenced by size or testing methods, could be made to correspond to values obtained by a recognized standard technique. The physical properties treated were the following: apparent specific gravity, apparent porosity, compressive strength, tensile strength, modulus of rupture (flexural strength), impact toughness, abrasive hardness, scleroscope hardness, Young’s modulus (modulus of elasticity), modulus of rigidity, specific damping capacity, longitudinal bar velocity, apparent Poisson’s ratio, and grindability. This initial phase of the U.S. Bureau of Mines program was followed by a systematic investigation of the physical properties of mine rock from all parts of the United States. Results were published in a series of four papers (WINDES, 1949, 1950; BLAIR,1955, 1956), the last of which contains a complete index of all the rocks examined. These papers, titled: “Physical properties of mine rock, parts I, 11,111, and IV”, probably present the most complete data on the important physical properties of the carbonate (and other) rocks. Selected information from these papers are shown in Table XX where they can be compared with values given by other authors. (1 960a,b) briefly reviewed testing methods and physical properties GILLISON given by KESSLER and SLIGH(1927) and WOOLF(1953). Woolf‘s paper is especially interesting because in it are described physical tests crushed stone must undergo before it can be evaluated for use as road building aggregate for state and federai highway development programs. A test treated by Woolf but often omitted by other authors is that of soundness, that is, response of the rock to alternate freezing and thawing. One manne: of determining whether material is “sound”, “questionable”, or “unsound” is by immersing several fragments or blocks of the material in a saturated solution of Na2S04 for 16-18 h, drying them in an oven, repeating the test five times, and noting the damage to the fragments or blocks.
TABLE V CRYSTALLOGRAPHIC DATA ON SOME ECONOMICALLY IMPORTANT CARBONATE MINERALS
(After GRAF,1961; DEER et al., 1962; and A.S.T.M., 1963a) Rhombohedra1 Z # of forCleavage cell edge ( A ) mula unitslunit cell
Twinning
a =b =4.990 c =17.061
6.31
2
(lOT1) perfect
R5
a=b=4.807 c=16.01
6.01 5
2
(1OTl) perfect
magnesite
R3c
5.615
2
(loT1) perfect
rhodochrosite
R3c
5.91
2
(loT1) perfect
(01T2) rare (lamellar twins)
siderite
R3c
5.77
2
(10T1) perfect
smithsonite
RJc
4.432
2
(loll) perfect
(01T2) rare (lamellar twins) (OOO1) rare
aragonite
Pmcn
-
4
(010) imperfect (1 10) poor
(110) common (lamellar and repeated)
wi therite
Pmcn
-
4
Pmcn
-
4
(010) good (1 10) poor (012) poor (1 10) good (021) poor (010) poor (1 10) good (021) fair
(1 10) always present, repeated
strontianite
a=b=4.633 C = 15.016 a = b =4.111 ~=15.66 a=b=4.69 c=15.30 a= b =4.653 c=15.028 a = 4.95 b= 1.95 C = 5.13 a = 5.26 b= 8.84 C = 6.56 a = 5.13 b= 8.42 C = 6.09 a = 5.195 b= 8.436 C = 6.152
(01T2) very common (OOO1) common (loil) not common (OOO1) common (10T1) common (1120) common (loT1) rare (0221) glide twinning (OOO1) translation gliding to [loll]
Mineral
Space group Unit cell (A)
calcite
R3c
dolomite
cerussite
Pmcn
-
4
(110) common (single, repeated, and lamellar)
.a v1
(1 10) common (repeated)
B P
malachite
P21/A
azurite
P21IC
a = 9.502 b= 11.974 c= 3.240 a = 5.008 b= 5.884 c=10.336
-
4
(001) perfect
-
2
(021) imperfect
(100) common
TABLE VI SOME PROPERTIES OF LIMESTONE USED IN KANSAS AS BUILDING
STONE^
(After KANSSSBUILDING STONE ASSOCIATION, 1964) Name
Texture
Colour
Absorption ( %)
Specific gravity
Weight Compressive strength Temperature(Wcubicft.) normal parallel Weak salt to bed to bed efect (IbJsq. inch) (Ib./sq. inch)
Onaga Chestnut Shell Neva Cottonwood Silverdale Benton Kansas Cream
fine grain coquinoid dense, fine grain medium to fine grain medium to fine grain fine grain fine grain
light buff chestnut white gray light buff buff creamy
7.6 5.4 3.1 6.2 9.4 4.9 9.0
1.956 2.118 2.440 2.21 8 2.109 2.259 1.674
122 132 I52 139 137 141 I05
9,629 4,806 22,600 11,292 6,189 11,589 4,520
9,775 5,625 18,800 11,525 8,505 10,650 4,710
none none no data none none none none
The Kansas Building Stone Association prepared a pamphlet which serves as a guide for architects and engineers who need a rapid reference to the most important properties of Kansas building stone. Compression test (A.S.T.M. C170-50) determined by C. Crosier of Kansas University Civil Engineering Department. Absorption and specific gravity (A.S.T.M. C97-47) and temperature-weak salt (A.S.T.M. C218-48T) tests were made by the State Geological Survey of Kansas.
1
w
VI
w
354
F. R. SIEGEL
TABLE VII SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. POROSITY AND BULK DENSITY (DRY AND SATURATED)
(After BIRCHet al., 1942, table 2-6) Lithology and age
Location
limestone limestone, Carboniferous limestone, Silurian limestone. Caddo Lime, Pennsylvanian Greenhorn Limestone, Upper Cretaceous limestone, sugary, quartz-free oolitic limestone chalk dolomite marble marble, 34 samples
Porosity ( %)
Buxton'
14.1 2.2-9.4 -1 1.4-6.3 Dundee, Mich. 0.9 Ranger, Texas 4.4 Crook Co., Wyo. 37.6
Monk's Park'
-1
Mitcheldeanl
-1
from 12 states in U.S.A.
25.6 20.3 17.642.8 8.6 1.1 0.4-2.1
Bulk density dry
saturated
2.31 2.342.59 2.53-2.64 2.63 2.57 1.74
2.45 2.43-2.61 2.59-2.65 2.64 2.61 2.12
2.14 2.16 1.53-2.22 2.54 2.65 2.66-2.86
2.40 2.36 1.962.40 2.63 2.66 2.68-2.86
w1hz0
Known or unknown location in Great Britain.
TABLE VIII SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. THERMAL EXPANSION OF ROCKS, TEMPERATURE INTERVAL OF 20-100"c
(After BIRCHet al., 1942, table 3-4) Lithology
Number of determinations
Average linear expansion coefficient
* limestones marbles
20 9
355
PROPERTIES A N D USES OF THE CARBONATES
TABLE IX SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. COMPRESSIBILITY OF ROCKS AT LOW PRESSURES
(After BIRCHet al., 1942, table 4-13) Pressure (kglcm2)
Lithology
dolomite
107p
enclosed
0 120 600 0 120 600 0 120 600
marble (Vermont) limestone, Pennsylvanian (carbonaceous)
37.1 25.4 14.8 180.0 33.1 15.0 29.2 27.5 23.5
unenclosed 11.9 11.9 11.9 13.9 13.8 12.6 24.7 24.5 24.1
' p = compressibility, in reciprocal bars, at the pressures given.
TABLE X SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. COMPRESSIBILITY OF ROCKS AT HIGH PRESSURES
(After BIRCHet al., 1942, table 4-14) Lithology
Location
Pressure (bars)
lO7/?1
marble (enclosed)
Colorado
7,000
13.8 (18°C)
Solnhofen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria Solnhpfen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria
6,000 6,000 5,000
13.6 (30°C) 14.2 (75 "C) 12.9 (6°C) 14.2 (100°C) 16.3 (270°C) 17.1 (476°C)
limestone (unenclosed, linear method)
lp=
5,000
5.000 5,000
compressibility, in reciprocal bars, at the pressures given.
F. R. SIEGEL
TABLE XI SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. ELASTIC CONSTANTS OF ROCKS AT ORDINARY PRESSURE AND TEMPERATURE^
(After BIRCHet al., 1942, table 5-4) G3 (dynes/cm2) (dyneslcm2)
Lithology
Location
E2
limestone
Knoxville, Tenn. Montreal, Que. Solnhofen, Bavaria
6.2 I 6.35 5.77
(2.48) (2.50) 2.31
dolomite
Pennsylvania-I Pennsylvania-2
7.10 9.30
3.23 3.62
marble
Dinant, Belgium Rutland, Vt.
7.24 5.24
(2.98) (2.07)
a4
Stress (kglcm2)
0.25 1 0.252 (0.25)
70-600 70-600
0.278 0.263
70-600 70400
Values of G or u in parentheses have been derived from the measurements by the use of the connecting equations for isotropic materials.. ?E= Young's modulus. 3G= modulus of rigidity. 4u= Poisson's ratio (dimensionless).
1
TABLE XI1 SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. EFFECT OF STRESS ON YOUNG'S MODULUS OF ROCKS, BY THE METHOD OF FLEXURAL VIBRATIONS OF LOADED BARS
(After BIRCHet al., 1942, table 5-5) Lithology _
_
Location _
~
limestone
Bedford, Ind. Bedford, Ind.
marble
Danby, Vt. Danby, Vt. Danby, Vt. Danby, Vt.
marble
Cockeysville, Md.
Orientation of axis'
Density (glcm3)
I
/I lI
/I
I I
EO2
Ea3
(dynes/cm2)
(dyneslcm2)
2.23 2.35
2.86 * 10" 3.48 * lo1'
2.97 * 10" 4.07. 10"
2.70 2.70 2.70 2.70
6.01 . 10" 6.48 . 10" 4.36. 10" 3.66. 1011
6.99 . 10" 7.24 . loll 6.94. 10" 5.81 . 10"
2.86
7.10 * 10"
8.84 * lo1'
1 Orientation of the axis of the bar with respect to the bedding plane. 2Eo= Young's modulus at zero stress. 3Ea= Young's modulus at a strsss not quite great enough to cause failure (500-1,OOO kglcm2).
351
PROPERTIES AND USES OF THE CARBONATES
TABLE XI11 SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. ELASTIC PARAMETERS OF CERTAIN ROCKS AT
4,000 kg/cm2 AND 30°C'
(After BIRCHet al., 1942, table 5-8) Lithology
Locat ion
E2 (dynes/ cm2)
G3 (dynes/ cm2)
P4
u5
(cmz/ dyne)
VP6
V87
(kmlsec)
(kmlsec)
limestone
Solnhofen, Bavaria
6.3
2.47
21.4
0.276
5.54
3.08
marble
Vermont
8.7
3.33
13.9
0.299
6.51
3.49
1 Values computed for the measured G and u by the use of equations for isotropic materials. The rocks were enclosed. 2E= Young's modulus. 3G= modulus of rigidity. 4 8 = volume compressibility 5u= Poisson's ratio (dimensionless). 6Vp= velocity of propagation of compressional waves in an infinite medium. 7 V8= velocity of propagation of distortional waves in an infinite medium.
TABLE XIV SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. RIGIDITY AND VELOCITY OF SHEAR WAVES AS A FUNCTION OF
PRESSURE^
(After BIRCHet al., 1942, table 5-9) Lithology Location
G2
P=I
vs3
P=500
P=4,000 P = l
P=500
P=4,000
limestone Solnhofen, Bavaria 1.96 Pennsylvania 2.67
2.20 2.88
2.47 3.00
2.75 3.15
2.91 3.27
2.47 3.34
dolomite Pennsylvania
3.49
4.20
-
3.5
3.87
-
marble
1.57
3.18
3.33
2.4
3.42
3.49
Proctor, Vt.
30°C. These results were obtained by a dynamical method, with All measurements made enclosed specimens. 2G= modulus of rigidity, in units of 10" dynes/cm2. 3Vs= velocity of shear or distortional waves, in km/sec. 4P= hydrostatic pressure, in kg/cm2. 1
358
F. R. SIEGEL
TABLE XV SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. STANDARD CRUSHING STRENGTHS OF ROCKS
(After BIRCHet al., 1942, table 9-1) Lithology
Number of localities
Average strength (kglcm2)
Range (kg/cm2)
limestone marble
216 76
960 1,020
60-3,600 3 1 O-2,620
TABLE XVI SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. SHORT TIME COMPRESSIVE STRENGTH OF UNJACKETED MATERIALS WITH CONFINING PRESSURE OF KEROSENE~
(After BIRCHet al., 1942, table 9-6) Lithology
Location
limestone
Solnhofen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria
2,560 2,600 3,260 4,000 5,970 > 13,000
marble
location location location location location
810 860 1,650 > 5J00 > 11,400
Strength pressure.
= p1-p2
Confining pressure (kglcm2)
not given not given not given not given not given
at failure, where pi = axial compressive strength and p2
Strength (kglcm2)
= lateral confining
359
PROPERTIES AND USES OF THE CARBONATES
TABLE XVII SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. THERMAL CONDUCTTVITY (AT1 atm PRESSURE)
(After BIRCHet al., 1942, table 17-4) Lithology
Temperature Conductivity K cal.lsec cm degree Wlcm degree
Location
( "C)
limestone
Solnhofen, Bavaria Solnhofen, Bavaria Solnhofen, Bavaria
limestone, (carbona- Pennsylvania ceous), parallel to Pennsylvania bed Pennsylvania
0 100 200
7.2 . 10-3 5.5.10-3 4.8.10-3
30.1 .lo-3 23.1 . 20 10-3
0 100 200
8.2 . 10-3 7.0.10-3 6.5 10-3
.
34.5.10-3 29.5.10-3 27.4 10-3
-
ceous), perpendicular Pennsylvania
100
0
6.1 . 10-3 5.4 . 10-3
25.5 .10-3 22.6.10-3
limestone, dolomitic Longford Mills, Ont. Longford Mills, Ont. Longford Mills, Ont. Longford Mills, Ont. Queenston, Ont. Queenston, Ont. Queenston, Ont. Queenston, Ont.
130 181 268 377 123 177 254 332
3.9. 10-3 3.8.10-3 3.7.10-3 3.2.10-3 3.4 10-3 3.4.10-3 3.3 10-3 3.2. 10-3
16 10-3 16 10-3 15 .10-3 13 . 10-3 14 .10-3 14 .10-3 14 .10-3 13 10-3
0
2.2.10-3 11.9 10-3
-
9.2.10-3 49.8 .10-3
100 200
9.3 10-3 8.0 . 10-3
38.9.10-3 33.3 10-3
30
5.~7.7.10-3
124 210 334
3.7 10-3 3.6. 10-3 3.3 10-3
limestone, (carbona- Pennsylvania to bed
chalk dolomite marble (17 varieties) marble (black)
St. Albert, Ont. St. Albert, Ont. St. Albert, Ont.
-
-
-
-
-
21-32
TABLE XVIII SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. ELECTRICAL RESISTIVITY
(After BIRCHet al., 1942, table 21-1) Lithology
limestone
marble
Location
Spain Missouri Kentucky France France France
Resistivity (Q em) 3.105 104 104-105 105 10'0
4 * 108
109 10'0
.10-3
-
16 10-3 15 10-3 14 .10-3
360
F. R. SIEGEL
TABLE XIX SELECTED PHYSICAL CONSTANTS OF CARBONATE ROCKS. DIELECTRIC CONSTANT
(After BIRCHet al., 1942, table 21-7) Lithology
chalk coral dolomite dolomite limestone marble marmorized limestone
Dielectric constant (range)
8.0-9.0 8.0-9.0 7.3 8.0-12.0 8.3 15.2
Research on newer testing methods is continuously in progiess. CROW(1963) presented an easy and precise optical method for determining Poisson’s ratio. DURELLI and FERRER (1963) have developed a simple and somewhat novel way of determining Young’s modulus and Poisson’s ratio, which could be practical when speed is required or when measurements have to be made inside furnaces. These authors expect the method to be especially useful for materials used in three dimensional photoelastic studies. Chemical composition The chemical property of the carbonates which most influences their potential usefulness is the chemical composition. Iron content, for example, is undesirable in limestones to be used as dimension stone, because with weathering, the iron will alter to the oxide, and stain the stone surface a reddish or brownish color. The American Society for Testing and Materials, the U.S. Bureau of Standards, the British Standards Institution, and similar organizations publish results of the investigations and give recommendations as to the limits of impurities that can be tolerated in carbonates for industrial use. Stringent control must be maintained on the chemical composition of the limestone used in the manufacture of many economically important products. Thus, for the production of the better grades of glass, a maximum of only 0.2 % iron oxide is allowable in the limestone used in the manufacturing process, and for flint glass this impurity must not exceed 0.03 % (JOHNSTONEand JOHNSTONE, 1961). It must be remembered, however, that the economics of industrial operations often dictates that a raw material, less pure than that recommended, be used so that the end product is obtained at a maximum profit. This is true in the metallurgical industry in which both the economics and the processes affect the acceptibility of a carbonate rock considered as a fluxing agent for the removal of silica, alumina,
PROPERTIES A N D USES OF THE CARBONATES
361
and other undesirable impurities from the ore rock. For the production of pig iron from iron ore in the blast furnace process, the limestone flux should contain less than 1.5% silica, and less than 0.1 % each of sulphur and phosphorus; but because of the logistics of individual operations, more silica and up to 0.5 %percent sulphur might be tolerated. Several large companies use a limestone with 4-15 % magnesia as a flux, although a purer limestone, if it were available at thesame cost as that being used, would contribute to a more efficient process. Similarly, for basic open-hearth smelting, the flux should be ideally at least 98% CaC03 with only 2 % of impurities such as alumina, silica and magnesium carbonate and but a trace of phosphorus; however, in areas where the purer material is not available, the flux might contain 5-10% magnesium carbonate, 1.5 % alumina and 1 % silica. The capacity for phosphorus removal is lessened by the higher magnesia content, and more flux must be used. Transportation costs involved in bringing a purer fluxing agent from a distant area, however, would cut profit margins so that the less efficient material is employed in many cases. Table XXI contains individual and composite analyses of selected carbonate rocks. There does not exist a standard list of components that should be determined in the chemical analysis of a carbonate rock. The analyses that are made are dependent, in some cases, upon the needs of the person requesting them and, in others, by the availability of facilities and equipment. Some of the differences in the type of compounds reported as part of a carbonate analyses are demonstrated in Table XXI. An obvious difference can be found in the method of reporting the loss on ignition in weight percent. Some laboratories equate this percentage with the COZ content of a carbonate rock, but investigations made by GALLE and RUNNELS (1960) and WAUGHand HILL(1960) demonstrate that this is not so. By accurately controlling the temperature of a muffle furnace at 550°C and l,OOO"C, values of the loss on ignition were obtained for carbonate and non-carbonate portions. In samples which contain small amounts of pyrite, the loss on ignition is complicated by the oxidation of the pyrite. Upon oxidation, the pyrite forms Fez03 and oxides of sulphur, which in turn react with CaC03 below the intermediate temperature to form CaS04, and thus cause a premature evolution of COZ. It is possible to obtain a true COa value by applying corrective measures as outlined by WAUGHand HILL(1960). It is evident that the results of a chemical analysis, however technically perfect, are representative of a carbonate rock only in so far as the sample supplied to the analyst is representative of the unit being studied. GALLE (1964) has shown that on samples taken along an outcrop, channel samples give more reliable and consistent analytical results than spot samples, and indicated that analyses of carbonate rock to be presented to a possible user should be made on channel samples. CLARKE (1924) gave an extensive listing of chemical analyses of carbonate rocks. GRAF(1 960a) presented tables of isotopic compositions and chemical analyses of carbonate rocks and sediments and of minor element distribution in
TABLE XX SOME PHYSICAL PROPERTIESOF SELECTED CARBONATE ROCKS~
Rock type
Location ASG
AP
CS
limestone (fossiliferous) limestone limestone (coarse white) limestone (kerogenaceous) limestone limestone limestone limestone limestone (chalky-smokey Hill-dry limestone (chakySmokey Hill) limestone (chalkyFort Hays-dry) limestone (metamorphic) limestone limestone (fossiliferous, oolitic) dolomitic limestone dolomitic limestone dolomitic limestone dolomitic limestone dolomitic limestone, glauconitic
Ind.
2.37
11-
10.9
1.6
1.9
3
27
4.84 2.06
3 12.4
WINDES(1949)
Ohio Ala.
2.69 2.83
28.5 24.0
2.9
8.6 6.6
10 7
58 66
7.97 3.64 7.64 3.51
4 15.4 4 14.2
WINDES (1949) WINDES(1949)
Colo.
2.25
16.6
0.4
3.7
10
56
1.8
1.0
22 7.8
WINDES (1949)
Utah
Ohio Ill. S. D.
2.78 2.68 2.6 2.68 1.71
28.0 23.0 8.0 22.3 2.4
2.2 1.9 13 2.6 0.3
2.5 2.5 1.5 3.0
9.3 9.6 2.6 7.4
52 61 33 52 13
9.43 9.56 4.2 9.87 0.65
3.93 3.96 2.0 3.84 0.37
2 3 4 3 10
WINDES (1950) WINDES(1950) WINDES (1950) BLAIR(1955) BLAIR(1955)
S. D.
2.0
2.0
0.3
10
0.75 0.5
S.D.
1.81
3.7
0.6
1.2
16
0.98 0.57
Calif.
2.80
15.3
0.6
3.2
42
4.51 2.15
7 10.9 0.05 BLAIR(1955)
Mo.
Okla.
2.67 2.56
1.2
18.9 16.8
2.0 2.3
3.1 2.9
8
59 41
6.49 2.66 7.45
6 13.5 0.24 BLAIR(1956) 0.20 BLAIR(1956)
Ohio Ohio Ohio Mo. Mo.
2.5 2.5 2.8 2.69 2.67
6.4 5.2 1.3 2.6 3.6
13 12 26 28.8 21.2
17 22 28 2.7 1.5
2.1 2.0 4.0 4.8 4.2
3.7
30 6.1 36 6.8 55 9.5 33 11.1 48 5.61
w. v.
0.7 0.9
0.26 6 2.7 0.8 26.0
8.3
TS
58
MRupIT
AH SH Y M
4.0
7.2 8.0 7.2
MRig SDC L B V P R
2.6 2.8 4.1 4.55 3.05
15.9-0.12 16.4 0.21 11 0.06 16.5 0.28 5.7 0.13
Reference
DWALLand ATCHINSON (1957) 13 6.3-0.13 BLAIR(1955) 5.0
7 10 4 3 >11
14 0.19 14 0.23 16 0.16 17.6 0.22 12.4-0.07
WINDES(1950) WINDES (1950) WINDES(1950) B~~m(1955) BLAIR(1955)
7
P
dolomite dolomite (gray) dolomite (siliceous) dolomite dolomite dolomite dolomite dolomite marble marble (white) marble limestone and marble marlstone (calcareous and dolomitic) limestone
Tenn. Tenn. Tenn. Ohio Ohio Ohio Ohio Ohio Md. Nev. N. Y. Nev. Colo.
2.84 2.76 2.77 2.4 2.6 2.6 2.6 2.4 2.87 3.2 2.72 2.79 2.31
0.7 2.3 1.2 8.6 3.4 4.0 3.0 8.5 0.6 2.3 1.8 0.4 4.9
46.7 52.0 35.6 13 23
3.8 3.8 2.5 11 19 14 14 14 2.8 2.4 1.7 2.6 1.8
15
19 11 30.8 34.5 18.4 22.3 21.9
marble
1.87-2.80 1.1-31.0 2.62.8 2.64-2.87 0.4-2.1 8-27
limestone dolomite marble limestone limestone marble (dolomitic)
2.66 2.70 2.63 2.34 2.56 2.80
5.9 14 7.1 13 4.6 11 1.8 3.4 2.7 7.3 1.9 6.4 2.3 7.8 2.1 4.2 2.7 8 3.0 3.9 4.3
7 9 6.7
427- 0.5-2 7ea 1-24 853 427- 0.6-4 6ea 8 4 2 1280 8 26 9 25 6 47
2.5-28.4 16.5 700 22 950
74 12.3 69 11.3 66 10.9 42 2.8 56 6.7 53 4.1 58 6.9 39 3.2 56 7.15 11.9 49 7.84 54 11.4 56 3.61
5.1 4.6 4.62 1.55
3.2 2.0 2.9 1.5 3.78 5.02 3.35 4.54 1.61
2 17.9 3 17.4 2 17.0 5 9.0 -0.09 5 14 0.05 6 11 0.03 3 14 0.18 4 10 0.07 4 13.7 4 16.6 3 14.5 1 17.4 14 10.5 0.11
1.2-3
*z
U
c,m m
TREFETHEN (1959)
4.35- 0.8-3.6 8.7 7.25- 1.3-6.5 10.15
3-6 7.6 12
WINDES (1949) WINDES (1 949) WINDES (1949) WINDES (1950) WINDES (1950) WINDES(1950) WINDES (1950) WINDES(~~~O) WINDES(1 949) WINDES (1949) WINDES (1949) WINDES (1949) WINDES(1950)
TREFETHEN (1959)
15
18
WCOLF(1953) WCOLF(1953) WOOLF(1953) KESSLERand SLIGH(1927) ATCHISON et al. (1962) ATCHISON et al. (1962)
Legend: ASG= apparent specific gravity; AP= apparent porosity (%); CS= compressive strength (1,OOO Ib./sq. inch); TS= tensile strength (1,OOO lb./sq. inch); MRup= modulus of rupture (1,OOO Ib./sq. inch); IT= impact toughness (inch/sq. inch); AH = abrasive hardness (10-3 resistivity x sq. inch/lb.); SH= scleroscope hardness (scleroscope units); YM= Young’s modulus? (106 Ib./sq. inch); MRig = modulus of rigidity (106 Ib./sq. inch); SDC= specific damping capacity ( x lod2);LBV= longitudinal bar velocity (1,OOO ft./sec); PR= Poisson’s ratio (dimensionless).
W
m w
TABLE XXI SELECTED COMPOSITE AND INDIVIDUAL CHEMICAL ANALYSES OF CARBONATE ROCKS
I talc. CaC03 calc. MgC03 CaO MgO
42.61 7.90 41.58
coz
1.o.i. d.1.o.i. (lO5/55OyC) d.1.o.i. (550/1,OOO"C) SiOz A1 2 0 3 Fez03 FeO acid. insol. Fe MnO MnOz
5.19 0.81
} 0.54
Ti02
KzO NazO Liz0
sos
S FeSz Pzos HzO (-) HzO (+) carbonaceous material SrO F
2
41.32 2.19 33.53 (34.55) 14.11 4.16 1.63
3
4
5
6
7
8
9
10
80.83 89.78 86.39 79.86 70.10 2.26 1.33 1.94 1.39 3.96 53.81 45.44 50.40 48.49 43.01 42.92 54.84 1.68 1.09 1.29 1.03 0.42 0.26 0.56 35.36 43.26 42.69 1.34 0.75 0.89 1.12 36.73 40.17 38.93 34.44 8.47 4.67 7.08 14.45 1.91 0.81 1.22 2.32 3.71 1.16 1.55 2.46 0.14
0.29
0.13
0.14
1.36 1.14 15.05 0.18 9.02 0.20 ),.I' 1.27
0.05
0.038
0.06 0.33 0.05 trace 0.05 0.09
0.16 0.71 0.39
0.08 0.25 0.07
0.05 0.07 0.02
0.07 0.12 0.04
0.18 0.39 0.10
0.04 0.25
0.03 0.02
0.04 0.06
0.03 trace 0.04
0.04 0.15 0.21(110"C) 0.56l 0.61 0.12
0.09
0.10 0.26 0.49 0.03
1.15 0.45
0.26
} 0.07
0.05 0.08 )19.03
0.09
0.23 0.69
4
Hz
vzos total
100.09
99.40
99.96 99.87 99.96 99.79 99.47 100.00 99.40 99.91
I Composite analysis of 345 limestones (CLARKE,1924). 2 Argillaceous limestone standard sample la, U.S. Natl. Bur. Std., dried at 105°C (NATIONAL BUREAU OF STANDARDS, 1954). 3 Composite analysis of 32 channel samples of the Toronto Limestone member of the Oread Limestone Formation, Pennsylvanian age, eastern Kansas, taken along the strike of the outcrop from the Nebraska border on the north to the Oklahoma border on the south (0.K. Galle, W. N. Waugh and W. E. Hill Jr., personal communication, 1964). Used for riprap, rubble. 4 Composite analysis of 32 channel samples of the Leavenworth Limestone member of the Oread Limestone Formation, Pennsylvanian age, eastern Kansas, taken along the strike of the outcrop from the K. Galle, W. N. Waugh and Nebraska border on the north to the Oklahoma border on the south (0. W. E. Hill Jr., personal communication, 1964). 5 Composite analysis of 32 channel samples of the Plattsmouth Limestone member of the Oread Limestone Formation, Pennsylvanian age, eastern Kansas, taken along the strike of the outcrop from the Nebraska border on the north to the Oklahoma border on the south. Used for aggregate, road metal, agricultural limestone (0.K. Galle, W. N. Waugh and W. E. Hill Jr., personal communication, 1964). 6 Composite analysis for 25 channel samples of the Kereford Limestone member of the Oread Limestone Formation, Pennsylvanian age, eastern Kansas, taken along the strike of the outcrop from the Nebraska border on the north to the Oklahoma border on the south (0.K. Galle, W. N. Waugh and W. E. Hill Jr., personal communication, 1964). Used for flagging. 7 Medway white chalk, Great Britain (JOHNSTONE and JOHNSTONE, 1961). Used for Portland cement manufacture. 8 North Wales limestone, Great Britain (JOHNSTONE and JOHNSTONE, 1961). Used for Portland cement manufacture.
365
PROPERTIES AND USES OF THE CARBONATES
12
I1
54.70 0.60 41.70 (43.00) 0.40 0.52 0.08
30.49 21.48 47.25 (47.52) 0.31 0.067 0.084
13 55.41 43.00
0.63 0.70
0.006
14
15
31.20 53.54 20.45 1.02 47.87
29.9 9.9 30.3
43.27 1.57 0.40 0.24
33.8 17.7 2.5 1.1
0.11 0.30 0.19
016
0.06
0.05 0.27
0.035 0.013
0.007
0.003
99.94
43.92
0.10
0.14 0.08
9.07 4.43 0.85 0.93 (0'54
1
0.1
0.9 0.8
0.04
0.05 0.16 0.14
0.007 2.6 0.006(105"C) )o.6
0.09 1.39
J
99.95 100.18 100.08
19
94.39 0.61 51.09 42.75 53.03 0.93 1.46 0.29 34.62 7.57 41.56
0.69
0.08